Uncertainty in the numerical simulation of groundwater DNAPLs migration is inevitable due to the complex and unknown hydrogeological conditions in the actual world. In order to overcome the computational burden caused by repetitive calls of the DNAPLs migration model in uncertainty analysis, this study is carried out, based on the traditional sparse grid (SG) surrogate model. In this paper, an improved SG method DA-LA-SG is proposed, which couples the local adaptive (LA) and dimensional adaptive (DA). The surrogate efficiency and accuracy of the proposed DA-LA-SG are verified through two analytical cases and a PCE migration laboratory experiment, and the proposed model is applied to the uncertainty analysis of indoor sandbox PCE migration simulation. The results show that in the early stage of establishing the surrogate model, the surrogate efficiency of LA-SG is better than or close to that of DA-SG and DA-LA-SG, but the efficiency of DA-SG and DA-LA-SG is gradually better than that of LA-SG with the increasing number of the interpolation nodes. DA-LA-SG performs the best. DA-LA-SG can be used to efficiently and accurately establish the likelihood function surrogate model of the PCE migration model, and analyze the uncertainty of parameters in PCE migration simulation. The posterior distribution of the model parameters is obtained, and it is found that the background medium permeability k₁, the fitting coefficient n₁ and the weak lens permeability k₂ can be identified clearly, but the background medium porosity μ_1, the weak lens porosity μ₂ and the fitting coefficient n₂ are basically evenly distributed, which are poorly recognized and insensitive to saturation observations.

Upscaling is often employed in numerical simulation of groundwater flow because the parameters are measured in the field on a support scale, which is much smaller than the discretization scale of the numerical model. A reasonable upscaling method can both improve the calculation efficiency and ensure the simulation accuracy. The method is applied to the upscaling of heterogeneous hydraulic conductivity fields in the numerical contaminant transport model of perchloroethylene (PCE), a typical non-aqueous phase liquid (NAPL) in groundwater, on the basis of the introduction of Laplacian with skin. The simulation results are also compared with those from the fine scale model and the coarse scale model upscaled by arithmetic average. The case study shows that the PCE contaminant transport model established by UTCHEM, which is upscaled by Laplacian with skin, can better describe the spatial moments (including the zero moment, the first moment and the second moment) of the plume over time, whether for the single source situation or dual sources situation. The absolute value of the relative error of the zero moment is less than 0.25%. Moreover, the coarse scale model only takes about 3% of the calculation time of the fine scale one, indicating that the methodology of Laplacian with skin is worth promoting in practice.

Ground water evaporation is an important process in water cycling. The bromide tracer is an effective tool to indicate the unsaturated zone flow process. It is of great significance to analyze the transport process of bromide under continuous evaporation condition and to estimate the effects of tracer injection conditions on estimating groundwater evaporation, and then to prove the applicability of bromide tracer for evaluating groundwater evaporation. In this study, HYDRUS software is used to build multiple sets of one-dimensional unsaturated water-solute transport models. Simulations were run to analyze the bromide transport under different conditions of water table depth and lithology, and to estimate the impact of tracer injection depth and concentration on evaluation of groundwater evaporation. The results show that: the bromide concentration peak moved upward fast due to the high intensity of groundwater evaporation when the vadose zone is thick and consisted of fine sediment. The different response of bromide transport to different conditions of vadose zone indicated the potential of bromide tracer to evaluate groundwater evaporation. The injection depth and concentration of tracer are important human factors affecting the evaluation results. The quantity of groundwater evaporation calculated by bromide tracer method was closer to the actual quantity when the injection depth is shallower. The injection concentration of tracer determines its peak concentration observed in the soil profile during the experiment period. The dispersion effect gradually enlarges the distribution range of tracer, thus the distribution of bromide concentration tends to be uniform in the profile and it is difficult to ascertain the position of bromide concentration peak. High injection concentration is conductive to prolong the evaluation period. Rainfall and the fluctuation of soil water content are potential negative factors affecting the evaluation results of field tracer test.

Geological structures, especially the neotectonics, play a controlling role in the occurrence of groundwater in bedrocks, and they are also the key factors for determination of well location and groundwater exploration. The north China anti-drought hydrogeology survey and drilling were carried out in the Linqu Basin in Shandong. Combined with the neotectonic movement in the parsed area and its expression form, some typical examples were select to examine the spatial distribution characteristics of groundwater types, lateral recharge of groundwater runoff conditions and characteristics of groundwater in space, etc. Control of the neotectonic movement of groundwater in the basin was analyzed, and the typical storage structures of groundwater under the control of the new tectonic movement were summarized. The research results show that (1) the Linqu basin is characterized by complex geological background, strong neotectonic activities, multi-phase and multi-directional activities, which has formed modern geomorphic pattern and stratigraphic structure of the basin and controlled the spatial distribution of different types of groundwater. (2) Under the control of the neotectonic movement, the western and southern parts of the basin were uplifted and karst was developed. The direct recharge areas of groundwater are located in the western and southern parts and the lateral runoff recharge constitutes the main source of groundwater recharge in the basin. (3) Under the influence of the tectonic activity intensity, lithological structure and groundwater runoff conditions, the outcropping carbonate rocks on both sides of the Wujing fault are strong runoff zones with underground karst, and the rocks are permeable but not water-rich. The Wujing-Yeyuan section is an underground karst water-rich area. The north of the Yeyuan reservoir and east of Shifotang-Linqu fault to the eastern boundary of the basin are the weakly water-rich areas of insoluble stratified rocks. In the eastern boundary of the basin, the fractures along the Shuangshan-Lijiazhuang fault are the relatively water-rich areas of the Cenozoic basalt with pore and fissures and ancient weathering fissured crust. (4) There are four typical types of groundwater storage structures in the Linqu basin, namely, fault belt type, contact belt type, horizontal layer type and complex type, etc. The belt type groundwater storage structure is the main type of storage structures in the basin, and it has also become the main target of groundwater exploration and well location in the study area.

The Jinan spring is a typical representative of karst springs in North China. Since the 1970s, the rapid urbanization process and excessive exploitation of groundwater have resulted in zero-discharge of the spring water. Although the measures to supplement the water source have been taken in recent years, the effect is not ideal. The basic reason is the lack of scientific basis for the selection of artificial supply sources. In order to determine the recharge ratio of different aquifers to the spring water in the Jinan spring area, according to the observations of the spring water level and water temperature, water quality index test, frequency analysis of spring water conductivity, and combined with the geological structure conditions of the spring area, the difference in spring water recharge sources is studied, and the recharge ratio of different aquifers to the spring water in the Jinan spring area is determined. The results show that (1) the recharge ratio of the karst aquifers to the Baotu Spring and Heihu Spring is different. The recharge ratios of the Baotu spring and Heihu spring from the Zhangxia formation aquifer are 31%-54% and 24%-31%, respectively, and supply water from the limestone aquifer of the Ordovician Limestone-Cambrian Fengshan Formation accounts for 45%-68% and 68%-75%, respectively. (2) The recharge sources of the Zhenzhu Spring and Tanxi Spring are the same. The recharge ratios of the Tanxi Spring and Zhenzhu Spring from the Zhangxia Formation are 60%-70% and 60%, respectively. The recharge ratios of limestone aquifer of the Ordovician Limestone-Cambrian Fengshan Formation are 15%-17% and 22%-25%, respectively. The recharge ratios of artificial recharge are 8%-21% and 13%, and the recharge ratios of pore water and fissure water are 6% and 5%-6%. (3) The characteristics of spring water temperature show that the groundwater of the Zhenzhu Spring and Tanxi Spring is mainly supplied by groundwater of deep circulation, and there are pore water and fissure water to supply the spring water, The influence of recharge water on the Zhenzhu Spring and Tanxi Spring is obvious. (4) Spring water level dynamics show that there are some differences in the source and direction of recharge between the Heihu spring and Baotu spring in dry and wet seasons, and the karst development in the limestone aquifer of the Ordovician Limestone-Cambrian Fengshan Formation is stronger in the Heihu spring area. Macroscopically, the spring water supply comes from the widely distributed Cambrian-Ordovician limestone area. Microscopically, the recharge intensity of different karst aquifers to the four major spring groups is obviously different. The Ordovician aquifer is an important recharge source of the spring water. The Ordovician limestone area is the site of artificial recharge source for maintaining the emergence of the spring water.

The reconstruction project of groundwater balance experiment site of Zhenzhou was rebuilded by Geo-environmental Monitoring Institute of Henan Province, belongs to one of the national groundwater monitoring projects, which is performed by China of Institute Geol-Environment Monitoring. In view of the key application problems of extending site-scale equilibrium test data to field production practice, this paper considers the combination of deterministic model (water transport equation) and stochastic model (regional vadose zone parameters). It is proposed to select 24 km² of the alluvial-producing area of the South Yellow River as a field test site to carry out regional variability study of the parameters of the vadose zone. Through limited sampling in the site, the parameter variability characteristics of vadose zone at any point in the site can be calibrated. With the help of regional meteorological data and the result of the established soil water transport mathematical model in the groundwater balance test site, the infiltration recharge of precipitation and the evaporation of phreatic water in the site are calculated, which can provide scientific basis for groundwater resource evaluation, geological environment assessment and groundwater resource sustainable development and utilization. Meanwhile, also lays a foundation for large-scale soil surface pollution assessment.

With the development of thermal energy and thermal power pipeline engineering and the large-scale application of ground-source heat pump technology in China, the problems of stress, deformation, seepage, and temperature coupling of rock and soil have become research hotspots in geotechnical engineering. Under a long-term loading, the deformation and strength of rock and soil bodies (especially the soft soil) change with time and are of obvious rheological characteristics. The traditional rheological models do not consider the effects of temperature and temperature rise mode on their parameters. In order to better reflect the rheological consolidation characteristics, the viscoelastic-plasticity of the soft clay is considered, the improved Nishihara model under thermo-mechanical coupling is established based on the Nishihara model by introducing the temperature expansion coefficient, and the stress-strain relationship is given. The analytical solutions are obtained for one-dimensional heat consolidation equation by using the Laplace transform and the inverse transform. The results show that when the consolidation pressure is constant, the temperature rise will accelerate the consolidation of the soil. When the temperature is constant, the pore pressure in the soil decreases with the increasing consolidation pressure. When the elastic modulus of the improved Nishihara model is increased, the speed of pore pressure dissipation and the consolidation of the saturated soil are accelerated. The thermal expansion caused by temperature of the soil particles has a very small effect on the dissipation of the pore pressure. The smaller the viscous coefficient, the faster the pore pressure dissipates and the faster the soil is consolidated. The experimental results are in good agreement with the thermal coupling of the viscoelastic-plasticity of the soil. The improved Nishihara model can better describe the thermal coupling characteristics of the soil.

The conventional vacuum preloading method takes a long time to treat the super soft soil foundation, and its reinforcement effect is sometimes limited. The vacuum preloading combined with heating technology is a new soft ground treatment technology proposed in recent years. In this work, a model test device with a temperature controlling regulator is designed. One of the typical soft clay in the Ningbo area is applied in this model test. A comparative study is carried out to evaluate the effects of the vacuum preloading combined heating and conventional vacuum preloading treatment. The development trends of temperature, pore pressure and settlement of the soft soil foundation under different heating temperatures (from normal temperature to 80 ℃) are analyzed in detail, and the physical and mechanical characteristics of the soil before and after different technology reinforcement are compared. The results show that compared with the conventional vacuum preloading, the vacuum preloading combined heating technology can accelerate the consolidation rate, reduce the post-construction settlement and improve the bearing capacity of the soft soil foundation. When the heating temperature is not high, the effect of vacuum preloading increases with the temperature, and this trend increases nonlinearly. When the temperature reaches a certain value, the strengthening effect of the combined thermal treatment technology will be attenuated or even counter-acting. According to the inversion analysis of consolidation settlement, the consolidation coefficient of the soft soil treated at 40 ℃, 50 ℃ and 60 ℃ increases by 30%, 35% and 5%, respectively, compared with the normal temperature. Considering the treatment effect and economy, heating to 40~50 ℃ is the suitable temperature range of the thermal foundation treatment technology.

Slag dump is a common man-made disaster body. Its stability is related to the road traffic in the region. The potential geological disasters caused by the slag dump also have a great harm to the people's production and life in the downstream areas. Based on the engineering practice of an abandoned slag yard along the Xuyong-Dacunzheng Railway, the accumulation process of the abandoned slag is reproduced by the physical simulation method, and the grading characteristics of the slag particle size and the slope structure characteristics of the abandoned slag deposit are studied. Based on the experimental results of the physical simulation and PFC discrete element numerical simulation, the deformation and instability process of the slope of the abandoned slag yard considering particle size classification is examined. The physical simulation results show that the formation of the waste slag deposits is a dynamic process. Under the interaction of gravity and particles, the size of the deposits is highly graded and uneven. From top to bottom, the average particle size increases, the density decreases and the void fraction increases. The discrete element PFC simulation study of the deformation and failure process of slope in the typical abandoned slag yard shows the stages of the back edge down fault, front bulging, potential slip surface formation and slip surface penetration.

There are many disputes about the effect of systematic bolts in tunnels, especially in weak surrounding rocks. One point of view is that the system bolts can reduce the deformation of the surrounding rocks, and the supporting effect is good, in particular, the side wall bolts can play a better supporting and restraining role. On the contrary, it is considered that the system bolts has no obvious effect, and the application of the system bolts delays the best time of initial support and leads to the increase of the surrounding rock deformation, but the surrounding rock deformation and stress condition are good after the removal of the system bolts. Based on the Ⅳ-level soft surrounding rock section of the Lijiazhai tunnel under construction in the Guizhou Yan-Yin-Song expressway project, a lot of field tests are carried out on the effect of systematic bolts. Three measurement sections are set under every condition, with and without the system anchoring bolts. The measurement includes pressure stress of the surrounding rock, both inside and outside stress of steel frame, axial force of systematic bolts, internal stress of jet concrete, settlement of tunnel crown, and horizontal convergence, etc. The test data of the comparative test sections and engineering verification indicate that (1) as the closure time of the initial support is prolonged by using the system bolts in tunnel, the surrounding rock pressure and steel frame stress are slightly larger than that without the rock bolts. Whether the tunnel is equipped with the system bolts, there is no obvious difference in the deformation and stress of the surrounding rock, so elimination of the system bolts will not affect the safety of the supporting structure. (2) As most of the systematic bolts are under pressure, the effect of the system bolts is poor. Obviously, the measures of application of the system bolts are too conservative, and there is a lot of room for optimization. However, the side wall bolts of the tunnel can play the role of the feet-lock bolts. When cancelling the system bolts, the feet-lock bolts should make sure to use. (3) The measures of erecting steel arches and cancelling the system anchoring bolts in the supporting structure in the Ⅳ-level soft surrounding rock section of the Lijiazhai tunnel can guarantee the initial support structure stability, and are technically safe and feasible.

Among the retaining wall, anti-slide pile, anchor rod and other retaining structures, the seismic performance of the anchoring system is better, and the possibility of slope instability is quite small. In order to study dynamic response of landslide to the anchor lattice beam under earthquake, large-scale shaking table model test is conducted. In this paper, the sinewave, Wenchuan wave and EL Centro wave are used as the input seismic wave, and the dynamic properties of the anchorage landslide and anchor rod under different excitation intensity and frequency are studied respectively. The results show that the dynamic response of the anchorage system under earthquake can be divided into three stages: the adaptive adjustment stage (0.05g-0.20g), the gentle anti-seismic stage (0.20g-0.40g) and the intense anti-seismic stage (0.40g-0.60g). The natural frequency and PGA amplification factor of the anchorage system shows the trend of "high→low→high". Under different excitation intensity and different excitation waves with different frequency spectrum, the strain mode of anchors in the same column is different accordingly. Under 15 Hz sine wave (close to the natural frequency of the anchorage system), obvious deformation in the upper part of the anchorage body occurs due to the resonance effect. The strain trend of anchors in the same column is changed from "C" shape to "Г"shape with the increasing excitation intensity. However, under the ultra-low frequency 5 Hz sine wave, the strain trend of anchors in the same column retains "Г" shape no matter what the excitation intensity is. Under the Wenchuan waves and El Centro waves, the strain trend of anchors in the same column shows "C"shape, for which the main reason is that the two seismic waves covers different spectral components. In the design of an anchorage landslide in the strong earthquake area, it is suggested that the top anchor and the foot anchor should be strengthened particularly to restrain the tensile cracks near the sliding surface and shear cracks at the slope toe.

High in-situ stress, groundwater erosion and construction disturbance may affect the construction of tunnels in carbonaceous slate rocks. It is of great significance to analyze the relationship of microfissures from the view of meso-view. The carbonaceous slate samples were selected in the actual engineering site, and the backscattering analysis was carried out by scanning electron microscope (SEM) to determine the components of the samples. The X-ray diffractometer was used to analyze the mineral compositions and their contents were obtained by using the MDI Jade-6 software. The stress-strain curves of carbonaceous slate under different water contents were obtained by the uniaxial compression test under different water-cut conditions, and the deformation characteristics and failure law of each stage were obtained. The results show that there are mainly quartz, muscovite and albite in the carbonaceous slate, and the extremely complete cleavage of the carbonaceous slate is easy to form penetrating fissures, and the maximum strength of the carbonaceous slate is close to the elastic deformation before it reaches the peak strength. With the increasing immersion time, the stress-strain curve of the slate gradually becomes obvious in four stages, and the stress drop slows down after the peak value. The main mechanical characteristics are as follows: the intermineral structure is destroyed by water lubrication, water wedge action and latent corrosion. The elastic modulus and the uniaxial compressive strength of rock decrease significantly, and the Poisson's ratio and peak strain increase slightly. Macroscopically, the angle of fissures changes slowly.

In the construction of underground shield tunnels, a large amount of slurry with high water content is produced. Due to the high moisture content of the slurry and the additives such as bentonite and foaming agent, the slurry is characterized by high water content, low permeability and strong plastic flow. It is prone to environmental pollution problems such as throwing and dripping during transportation, and it occupies a lot of land resources when the slurry is piled up. Sometimes improper stacking also pollutes the environment and even forms geological disasters. In this work, the experimental research on the mud-water dehydration technology of the tunnel shield slurry is carried out, and an electro-osmosis combined with vacuum negative pressure drainage test device is developed, in which vacuum negative pressure, electro-osmosis and vacuum negative pressure incorporated with electro-osmosis technology are used for the slurry that is initially treated by sedimentation to conduct mud-water dehydration test. The test results show that the drainage effect of the combined method is better than that of the single method alone. The combined method not only discharges seepage bound water in the slurry but also discharges free water. The moisture content of the treated slurry is greatly reduced (close to the plastic limit), and the slurry is effectively hardened. The order of the mud-water dehydration method is first to perform the electro-osmotic method and then to perform the drainage method. This research effectively solves the problem of the mud-water dehydration, and is conducive to green and safe transportation and effectively reduce transportation costs. More importantly, the treated slurry can be directly utilized.

The study of the correlation between compression characteristics and pore size distributions (PSDs) is one of the ways to explore the macroscopic and microscopic relationship of soils. To study the pore structure at different depths with similar initial void ratio and different compression characteristics and the pore structure changes at all different depths after undergoing a loading and unloading, a series of compression and mercury intrusion porosimetry (MIP) tests were simultaneously conducted on the undisturbed Yangzhou clayey soils at different depths. The test results show that the PSD of the undisturbed Yangzhou clayey soils at depth from 3 to 21 m is unimodal. The pore-size mainly distributes between 0.2 and 5 μm. The compression performance is closely related to the PSD, and the more concentrated the PSD, the smaller the compressibility. The soil samples at depths 12, 15 and 18 m have wider PSD, much more small pores, greater compressibility and stronger structure than other depths. The compressibility at different depths with similar initial void ratio is different with different PSDs. After undergoing a loading and unloading, the proportion of the medium pores in each soil layer decreases, the PSD moves toward the small pore diameter, and the proportion of the large pores does not change much, while the cumulative pore volume decreases at depths 12, 15 and 18 m are larger, so the decrease in the proportion of the medium pores at the 12, 15 and 18 m soil samples is more pronounced. The research results are of reference value for the study of the correlation between the engineering characteristics and microstructure of clayey soils.

Fiber length, fiber content, water content and dry density are the main influencing factors of the strength of fiber red clay. The orthogonal experimental design method is used to study the effect of multi-factor coupling on the shear strength indexes c and φ of the fiber red clay. The test results are analyzed by the range analysis and variance analysis, and the optimal preparation process of c and φ and the significance of each influencing factor are determined. Based on the multivariate nonlinear regression theory, a multivariate nonlinear regression model of multi-factor for c and φ of the fiber red clay is established by sing the SPSS software. The experimental and analytical results show that the main order of the influence of four factors on the values of c and φ of the fiber soil is: water content＞dry density＞fiber content＞fiber length, in which the water content has a significant effect on c, dry density and fiber content. Dry density and fiber content have a certain effect on c, φ is obviously affected by water content and other factors have no obvious influence on φ. The change of level of each factor affects c more than φ. The multivariate nonlinear regression model of c and φ shows that the correlation coefficients of c and φ models are higher and more significant, and the linear relationship between the predicted and actual values is obvious, and the reliability of the model is determined. The research results are of important guiding significance for further research on the engineering characteristics and curing mechanism of the fiber-modified red clay.

The marshy and lacustrine clay, which is of special engineering properties different from other soft clays, formed in the special sedimentary environment that lakes and marshes were drying and shrinking due to climate change. To investigate the engineering geological characteristics of the marshy and lacustrine clay in the Hengshui Lake area, the sedimentary environment, sedimentary history, distribution characteristics and stratigraphic structure of the marshy and lacustrine clay are discussed respectively. Moreover, the physico-mechanical indexes, mineral compositions, particle size distribution and microstructure features of the marshy and lacustrine clay are compared with other soft clays. The results show that the physical indexes of the marshy and lacustrine clay are close to or reach the soft clay, but the mechanical indexes of the marshy and lacustrine clay are better than those of the soft clay. When the stress level in soil exceeds the structural yield stress, the strength and compression of the marshy and lacustrine clay will abruptly change since the marshy and lacustrine clay possesses significant structural properties. The content of colloidal particles in the marshy and lacustrine clay is 39%, which is obviously higher than other soft soils. Meanwhile, high content of magnetite in the marshy and lacustrine clay, which makes it easy to forms iron oxide cements, enhances the cementation characteristics of soil, resulting in forming a more stable structure skeleton. It can be seen that the mismatch between physical indexes and mechanical indexes of the marshy and lacustrine clay is responsible for its special mineral compositions and microstructures. The difference in soil particle morphology, soil particle contact and microstructure are greatly responsible for the difference in the engineering geological characteristics between the and lacustrine clay and soft soils in other areas.

With the increase of extreme heavy rainfall events, large-scale slides occurred at many gentle slopes in the piedmont in Nanjing, which is inconsistent with the traditional view that gentle slopes in the piedmont are in favor of the overall stability of the mountains. The analysis of the engineering geological characteristics of the Youzi Mountain landslide shows that it is a typical rainfall-induced landslide preliminarily. At the same time, the sliding mechanism of the gentle slope is studied based on the stratigraphic lithology, geomorphological characteristics, rainfall conditions and engineering activities in the landslide area. The results show that the natural slope of the mountain in Nanjing is of unique stratigraphic structure characteristics: the upper part of the mountain bedrock is bare and the topography is steep; the middle and lower parts are widely covered with the Quaternary unconsolidated sediments, and the slope is gentle, forming a gentle slope in the piedmont. The surface of gentle slope is dominated by fine-grained soil, while the middle and lower layers are dominated by coarse-grained soil, gravel or weathered rockmass, forming a special "binary stratigraphic structure". Under the extreme heavy rainfall, the upper part of the mountain is basically stable, and the bare rockmass fractures are in favor of rainfall infiltration. The middle part of the mountain by precipitation is prone to circular sliding, and the lower part of the gentle slope is easy to form a "temporary confined water", which is prone to landslide under the combination of downslide force of the middle slide body. GeoStudio software is used to calculate and analyze the deformation of the slope. The upper part of the slope first reaches the limit equilibrium state. Since the lower part of the temporary groundwater in the confined aquifer cracked the thinner soil layer in the slope foot, the mountain slipped as a whole, which effectively verifies the formation mechanism of the landslide. The research results are of great significance for the management of similar landslide disaster in Nanjing.

The Karakoram Highway (KKH) is an important part of the China-Pakistan Economic Corridor. However, geological disasters along the route are frequent, posing a serious threat to the normal operation of the highway. In particular, the geological environment of the Gaizi valley in China is more complicated, under the precipitation and induced earthquakes, geological disasters such as collapse, landslide and mudslide occur frequently. This study uses SBAS-InSAR technology combined with field verification to carry out surface deformation monitoring and early identification of geological disasters in the Gaizi valley, the time serious surface deformation information of the Gaizi valley section is obtained, and the annual average deformation rate and cumulative deformation variables of each deformation point are extracted. The 10 km buffer centered on KKH is selected as the research scope, and the deformation rate of the LOS (Line Of Sight) in the study area from 2016 to 2017 ranging from -76 to 28 mm/a is obtained by the SBAS-InSAR method. Combined with the slope and aspect of the study area and the geometrical attitude of the satellite acquisition data, the LOS deformation is converted to the slope direction, and the maximum deformation rate value along the slope direction is -157 mm/a. Based on the surface deformation rates of the slope direction, 449 disaster points covering the study area are obtained by field investigation, including 31 landslides, 416 unstable slopes and 2 glacial movements. Through remote sensing interpretation and field verification, 23 debris flows are identified in the area. By using the TRMM precipitation data to analyze the time series deformation curve, the occurrence of regional landslides and unstable slopes is related to strong precipitation, and the sliding phenomenon lags behind the occurrence of heavy precipitation. Therefore, we should focus on the occurrence of abnormal precipitation. The results provide a scientific basis for early identification and prevention of disasters.

So far, most of the researches on karst collapses have focused on shallow karst of less than 100 m in depth, while the deep covered karst collapses of more than 100 m in depth were seldom examined. Therefore, there are no mature survey methods and standards. Considering the cost and applicability of geophysical methods, the deep karst collapses are investigated indirectly because of the large thickness of overburden. In this paper, an application example in the eastern part of the Beijing plain is given. Considering the main controlling factors of deep covered karst collapses, including fractures, fragmentation degree of the carbonate rock roof, thickness of the overburden cover, and properties of the soil layer at the bottom of overburden, the authors discuss the applicability of five geophysical methods, including the high-precision gravity survey, anti-interference electric sounding, controlled source audio-frequency magnetotellrics (CSAMT), microtremor survey and high-density resistivity method. The results show that in the geophysical investigation of deep karst collapses in the plain area, the better methods of fracture geometry features detection are the gravity survey and CSAMT. The anti-interference electric sounding and CSAMT are good at detecting fragmentation degree of the carbonate rock roof, and the suitable methods of overburden thickness detection are CSAMT, microtremor survey and high-density resistivity method. The methods of overburden structure detection give high priority to the microtremor survey and resistivity method.

Ground fissure is one of the most typical urban geo-hazards in Xi'an, and the stratum deformation and ground settlement caused by metro tunnel construction in the ground fissure section is a prominent engineering geological and geotechnical engineering problem. In this paper, the Xi 'an metro line 6 is taken as the engineering background, and the ground settlement and tunnel deformation induced by the excavation of CRD method in the ground fissure section is simulated with the finite element method. The results show that the ground surface settlement caused by excavation is characterized by an inverse s-shaped change and the excavation footage of the hanging wall have a greater influence range than that of the footwall in the ground fissure section. The ground surface settlement in the center line of the tunnel is staggered in the ground fracture zone and a concentrated settlement area appears at 5 m near the hanging wall of the ground fissure. The influence area of the shallow-buried excavation on the surface is about 80 m in ground fissure zone, whicht is about 45 m in the hanging wall and about 35 m in the footwall. In this range, the impact of the underground excavation on the nearby surface structures should be considered. In the process of excavation, the ground settlement process of the hanging wall is longer and larger than that of the footwall and the lateral deformation laws of the ground surface conforms to the Gaussian curve distribution. The settlement values of the hanging wall are larger than that of the footwall, and the width and settlement value of the tunnel groove increase at the position of the hanging wall near the ground fissure. The maximum settlement of the arch roof occurs at 5 m away from ground fissure, with a value of 25 mm, while the uplift deformation of 27 mm occurs on the arch bottom at the ground fissure zone. The deformation of the arch top and arch bottom is staggered near the ground fissure zone. The influence areas of the shallow-buried excavation of tunnel on the arch roof and bottom are 50 m and 55 m, respectively. The tunnel lining near the hanging wall of the ground fissure zone during excavation construction should be supported in time to prevent soil collapse and lining deformation. The research results can provide a scientific basis and technical guidance for the underground excavation construction of the metro tunnel crossing ground fissure zone in Xi'an.

A thermal reservoir consists of a matrix system and a fracture system. There is a big difference in the way of heat transfer between the two systems. Considering only the matrix permeability or the fracture permeability is not consistent with the actual heat recovery process. It is only by clearing the law of the change in the geothermal reservoir under the double permeability of the fracture-matrix that the geothermal resources are developed more reasonably and effectively. The GR1 well in the geothermal field of the Gonghe Basin in Qinghai is taken as the research object. Based on the thermal fluid-solid coupling theory, the COMSOL numerical simulation software is used to establish the dual-porosity medium permeability heat transfer model. The changes in reservoir temperature field, strain field, stress field and displacement field are obtained by considering different matrix permeability (0, 1×10^-18, 1×10^-16 m²) and fracture permeability (5×10^-11, 1×10^-10, 2×10^-10 m²). The results indicate that (1) when only considering the fracture permeability, the reservoir production life and output temperature will be overestimated; the compressive strain and settlement of the reservoir during the heat recovery process will be underestimated, indicating that the matrix permeability cannot be ignored. (2) The optimal fracture permeability is 1×10^-10 m², which is most suitable for thermal mining. The fracture permeability is 2×10^-10 m² and the reservoir life is less than 50 a. (3) At the initial stage of heat recovery, the maximum compressive strain increases by 2.74 times with the permeability of 2×10^-10 m² compared with the fracture permeability of 1×10^-10 m². When heating 40 a, compared with the permeability of 5×10^-11 m², when the fracture permeability is 2×10^-10 m², the reservoir settlement increases by 0.164 05 m, and the settlement area is expanded by about 3 times. The conclusions obtained provide a reference for the study of permeability and reservoir variation in the dry hot rock mining process in the Gonghe Basin in Qinghai.

This paper reviews the extraordinary development of Hydrogeology & Engineering Geology. Based on the data of www.cnki.net, CD-ROM edition of the 50th anniversary of the founding of the publication and the digital full text of the later 10 years, the total amount of documents and academic papers from 1957 to 2018 are obtained by using the method of information metrology, which are 6 901 and 5 834, respectively. Change in the number of papers are characterized by large fluctuation in the earlier period and relatively stable in recent years. The distribution of authors and institutions shows a high consistency between the two. That is to say, the organization of high-volume authors is also a high-volume organization. Statistical results of funding sources show that the number of funded papers has increased from 18% in 1994 to the highest 95% (2017), and it has maintained a high level of above 90% in recent years. The level of funding is mainly supported by the National Natural Science Foundation of China, Geological Prospecting Project and the Ministry of Education, and there are more provincial and municipal funded projects. According to the development history of the journal, it is divided into three stages: foundation-laying, stagnation and development. The important contents and directions of the development of different hydro-environmental geological undertakings reflected in the literatures at the foundation-laying and development stages are analyzed. It is found that this journal is closely combined with national economic construction, and the purpose of running journal which is to integrate theory with practice is reflected.