Grout Curtain Research Articles

Structural alternatives of high embankment dams

At present the types of seepage-control elements made of non-soil materials are worked out for construction of ultra-high embankment dams. We made assessment of workability of a number of new structural designs of seepage-control elements for embankment dams such as concrete core, grout curtain, massive face, combined seepage-control elements. The assessment was made by analyzing the results of numerical modeling of more than 200 m high dam stress-strain state. It was revealed that the most perspective way of constructing high embankment dams is use of combined seepage-control elements. The operative structures are structures consisting of a reinforced concrete face and a vertical structure (like a diaphragm or a curtain), made of clay and cement mix. Use of internal seepage-control elements made of rigid materials in high embankment dams is dangerous.

The results of numerical simulation of the work of the geotechnical screen of a sparse row of piles

This article is devoted to a computational investigation of the work and the effectiveness of using a geotechnical screen from a sparse row of piles to reduce the yield of the building foundation of surrounding buildings caused by the installation of a reinforced concrete “diaphragm wall”, which serves as a barrier for a deep excavation, opened for the construction of a new building erected in constrained urban conditions. As a result of studies carried out using the MIDAS GTS NX software package, it was shown that the curtain grouting depends on the parameters of its design, which include the axial distance between piles, their diameter and length, and the location between the trench under the “diaphragm wall” “And the protected building, reduces the precipitation of buildings surrounding the buildings, caused by digging up the trench, by 50-60%. Analysis of the obtained data allowed us to establish the most significant parameters affecting the efficiency of geotechnical use on the screen of the rarefied number of stilts, define the limits of the maximum efficiency of its use and give practical recommendations for its design.

Practice of water inrush and mud grouting in fractured fracture zone

Start your Through the practice of curtain grouting in the fault zone F2 of Zhongjiashan Tunnel in Jiangxi Province, we explored effective methods for the treatment of fault crushing zone, including key parameters such as grouting drilling design and grouting material selection. The research results show that the full-section grouting method is to treat The effective means of water and mud outburst disasters in the fault crushing zone can be used as a reference for a full-section grouting method. The cement grout and the cement-water glass slurry can be used together to provide an effective grouting material for the curtain grouting treatment in the fault crushing zone; In the implementation of full-section curtain grouting, an outside-in grouting method should be adopted.

Study on Comprehensive Treatment Method of Curtain Grouting in Water-Rich Sand Layer

The excavation of the Ling-Huang section of Qingdao Metro exposes the unfavorable geology of the rich water sand layer, and this paper explores the effective means of controlling water-rich sand layers through curtain grouting control in key areas. In turn, through the analysis of engineering hydrogeological conditions, difficult point analysis, grouting reinforcement circle design, grouting drilling design, grouting parameter design, dynamic control of grouting process, etc., a comprehensive grouting treatment method is formed. And through the engineering test section for actual verification. The results show that the curtain grouting in the key areas has better control effect on the water-rich sand layer, and the efficient use of the slurry is realized, which ensures the stability of excavation. Can provide reference for similar projects.

Practice Study on Grouting Treatment Engineering of Broken Rock Mass

The fractured rock mass is the unfavorable geology often exposed during the construction of the subway. Combined with the problem of seepage water in the side wall of the Xiangjiang Road station of Qingdao Metro, it explores effective means to control the fractured rock mass. Through the engineering hydrogeology and the surrounding environment analysis of the foundation pit, the ground curtain grouting scheme of the whole station is adopted to block the groundwater outside the pit of the station. The grouting borehole design, grouting parameter design, grouting dynamic monitoring control, etc. are determined in turn, wherein the grouting material adopts 800 mesh ultra-fine cement, fully considering the crack opening problem. The grouting method adopts forward section grouting, which fully considers the problem of poor integrity of fractured rock mass. Finally, the effectiveness of the grouting method is verified by engineering test section. The research results show that the super-fine cement ground surface curtain grouting method can better solve the problem of seepage water in fractured rock, and can provide reference for similar projects.

An experimental study on microstructure of leachate-polluted stabilized clay

Clay-solidified grouting curtain (CSGC) is a new kind of vertical barrier for remediating unregulated waste disposal sites in China that combines vertical-barrier and cement-based solidification-stabilization treatment techniques. The cement, stabilizing agents and landfill leachate clearly influence penetration. Although CSGC is becoming widely used because it is effective and economical, little is known about how it works. There is no clear consensus on the penetration mechanism, especially under actual continuous leachate percolation. The present work, therefore, studies the microstructure of CSGC under actual continuous leachate percolation. The cement and self-development stabilizing agents (CERSM-B) and their combined effect on the cumulative intrusion and pore size distribution were investigated using mercury intrusion porosimetry and scanning electron microscope images. The experimental results demonstrated that the unhydrated cement particles first create a large pore space. With increasing cement content, cementation products fill the large pores, thus decreasing the total pore volume. Fine-needle hydration ettringite crystal and calcium silicate hydrate gels are found when the cement content is below 15%. Stabilizing agents (CERSM-B) play an important role in the microstructure of CSGC. A close structure of flaky crystals with small, infrequent pores can be observed in samples treated with stabilizing agents (CERSM-B). However, adding too many stabilizing agents (CERSM-B) may increase the continuity of macropores. The peak pore size distribution and corresponding pore size increase with increasing dosage of stabilizing agents (CERSM-B). In engineering applications, the recommended range of cement and stabilizing agents (CERSM-B) is 15–20% percent clay and 7.5–10% cement.

Detection and treatment of water inflow in karst tunnel: A case study in Daba tunnel

In a karst tunnel, fissures or cracks that are filled with weathered materials are a type of potential water outlet as they are easily triggered and converted into groundwater outlets under the influence of high groundwater pressure. A terrible water inrush caused by potential water outlets can seriously hinder the project construction. Potential water outlets and water sources that surrounding the tunnel must be detected before water inflow can be treated. This paper provides a successful case of the detection and treatment of water inflow in a karst tunnel and proposes a potential water outlet detection (PWOD) method in which heavy rainfall (>50 mm/d) is considered a trigger for a potential water outlet. The Daba tunnel located in Hunan province, China, has been constructed in a karst stratum where the rock mass has been weathered intensely by the influence of two faults. Heavy rain triggered some potential water outlets, causing a serious water inrush. The PWOD method was applied in this project for the treatment of water inflow, and six potential water outlets in total were identified through three heavy rains. Meanwhile, a geophysical prospecting technique was also used to detect water sources. The connections between water outlets and water sources were identified with a 3-D graphic that included all of them. According to the distribution of water outlets and water sources, the detection area was divided into three sections and separately treated by curtain grouting.

Mathematical modeling of curtain grouting parameters for the roadways flooding prevention

The object of research is the process of flooding the roadway in the zone of influence of irrigation fields. One of the most problematic places is the influence of such technogenic factors on the groundwater level as irrigation fields and roads, the prevailing natural factors. Excess moisture content reduces the carrying capacity of the soil, which leads to accelerated destruction and shortening of the road life. In such cases, a road with drainage problems requires more frequent repair and rehabilitation than the one on which the drainage system is functioning normally. Therefore, the cost of the device coverage should be compared with the cost of supporting wastewater. To maintain the roads and prevent their flooding, constant monitoring of the state of the groundwater level (GWL) and a forecast of its changes are necessary. In the course of research, mathematical methods are used (analytical solution of differential filtration equations involving the Maple computer program) for mathematical modeling of the curtain grouting parameters. As well as methods of environmental and economic assessment and comparative analysis to determine significant factors influencing the GWL and the impact of GWL on the environment. An engineering measure is proposed to protect the roadway from the harmful effects of groundwater, providing for the establishment of curtain grouting along the road. The mathematical modeling of the parameters of the curtain grouting, which will make it possible to effectively use the curtain grouting in the fight against flooding. From the Polubarinova-Kochina equation of the liquid medium motion, the Dupuit equation is obtained, which was used to solve the stationary problem of determining the flow rate of water through the curtain grouting. Then it is solved the stationary problem of determining the flow rate of water through the curtain grouting. It is established that the use of curtain grouting is effective even at such parameters: К f ≤ 0.7 m/day, with a greater length and a smaller deepening of the curtain itself. The obtained calculations of the parameters will allow the use of curtain grouting in various industries to protect against flooding of various objects.

Grout Curtain Construction At Bolivar Dam, Ohio

Abstract Bolivar Dam, located in eastern Ohio, is an embankment dam constructed by the U.S. Army Corps of Engineers in 1937 as part of the Muskingum River Basin Project for flood control. As a result of seepage concerns observed at the dam during several flood events over the life of the project, seepage reduction measures, including a partial-depth seepage barrier wall through the embankment and a grout curtain in the left abutment, were designed and constructed. These dam safety modifications were constructed between 2014 and 2016. During flood events, Bolivar Dam experiences excessive seepage through the glacial outwash foundation as well as through a network of open joints within the left bedrock abutment. Seepage in the bedrock abutment could erode/scour the dam embankment at the bedrock contact, potentially leading to dam failure. To lower this potential risk of dam failure in the left abutment, a grout curtain was constructed between the new seepage barrier wall and an existing grout curtain across the emergency spillway. The new grout curtain is designed to impede groundwater seepage, resulting in reduced groundwater velocity/energy downstream of the grout curtain, thereby decreasing its potential to scour or transport fine-grained embankment material. The double-line grout curtain is approximately 65 ft (19.8 m) deep and 400 ft (121.9 m) long and was completed in November 2015 as part of a major dam safety modification project. Two thin limestone units encountered during drilling proved to be problematic and posed various challenges during construction. It was common during drilling to lose water circulation within the vicinity of these limestone units, which then required the use of downstaged grouting methods. The majority of the grout volume for the project was placed within these downstaged intervals. This article presents the risk-informed decisions that were made during both design and construction of the grout curtain and includes various lessons that were learned during this process.

Contribution of spectral coherency analysis and tracer test to study leakage at the Doosti Dam reservoir, Iran and Turkmenistan

The Doosti Dam was built across the Harirood River on the border between Turkmenistan and Iran. During the reservoir impounding, leakage occurred as new springs through the sandstone layers of the Pesteleigh Aquifer and limy sandstone and limestone layers of the Neyzar–Kalat Aquifer, at the right abutment of the dam. To evaluate the grout curtain operation, a tracer test was carried out by injection of Uranine in a borehole located at the upstream of grout curtain in the Pesteleigh Aquifer. Tracer test results demonstrated a diffuse flow component through the grout curtain in the Pesteleigh Aquifer, but no tracer was detected at the main leakage point, SP1 Spring, emerged downstream of grout curtain from the Neyzar–Kalat Aquifer. Using the spectral coherency function, the lag time between changes in the water level of the injection borehole and water level in the tracer detected boreholes or discharge of the tracer detected springs was determined. Linear regression analyses indicated that the estimated lag time by the time series analysis was close to the first arrival time of the tracer. Therefore, the estimated velocities based on the lag time of time series could be considered close to the calculated velocities based on the first arrival time of the tracer. The estimated groundwater velocities based on the time series analysis ranged from 3.91 to 20.31 m h−1, showed that diffuse flow dominated pathways from the reservoir toward the downstream boreholes in the Neyzar–Kalat Aquifer, while conduit flow was present within the pathways toward the SP1 Spring. Regarding the reservoir volume, the negligible amount of leakage at the maximum water level of the reservoir confirmed well overall operation of the grout curtain at the dam site.

Alteration characteristics of granite contact zone and treatment measures for inrush hazards during tunnel construction – A case study

Several large-scale mud and water inrush events occurred during excavation of the Denghuazhai Tunnel at a depth of 175 m in the contact zone between geodic granite and tuff. By analyzing the inrush process, the characteristics of the inrush hazards, such as high pressure, abundant water, high mud and sand content and strong destructive power, were revealed. In addition, the inrush hazards were intermittent, uncertain and sudden. An intrusive contact zone between geodic granite and tuff was revealed by regional geological investigation. Large-scale alteration occurred both in geodic granite and tuff near the contact zone. Petrographic analyses indicated that alteration to albite, sericite and kaolinite occurred in geodic granite, and alteration to quartz and montmorillonite took place in tuff gradually toward the contact zone. Furthermore, the changes were gradational within and between various alteration grades. The closer to the contact zone, the higher degree of alteration, the less the primary minerals including quartz, K-feldspar and plagioclase, the more the secondary minerals such as sericite and clay minerals. Tests on porosity, saturated water content and uniaxial compressive strength indicated that alteration led to significant deterioration of physical and mechanical properties of rocks (except for silicified tuff). Especially, for the zonal clay in the central area of contact zone, the physical and mechanical properties were poor and obvious swelling, disintegration and argillation were observed. Tunnel excavation triggered swelling, disintegration and argillation of clay, leading to several large-scale inrush events. In terms of treatment of inrush hazards, first of all, a comprehensive exploration method based on petrographic analyses, geophysical detection and borehole drilling was established according to the alteration characteristics, so as to identify the scale and composition of the altered zone. The principle of “consolidation before removal” was adopted to deal with the inrush deposits for breach sealing and reinforcement. Energy release and stress reduction during tunnel construction and regular drainage during operation were achieved by dewatering measures, namely, “drainage supplemented by sealing, water drainage and solids remaining”. Reinforcement measures, including full-face curtain grouting and double-layer pipe sheds, were adopted to reinforce and seal the highly disturbed rock and soil in advance. Finally, technical measures, including “bench excavation, enhancement of support stiffness and timely installation of secondary support”, were employed to effectively prevent large deformation in disturbed rock masses. With the above measures, the left and right tunnels of the Denghuozhai Tunnel have passed through the altered zone successfully.

Interpretation of high pressure pack tests for design of impervious barriers under high-head conditions

High pressure packer test (HPPT) is an enhanced constant head packer test widely applied for characterizing the permeability or coupled hydromechanical properties of fractured rocks under high water pressure condition, but it remains an issue about how to choose a representative quantity from the test data for the design of impervious barriers in high-head geotechnical projects. In this study, the typical type curves of HPPTs are summarized and related to the intactness of rocks, flow condition in fractures and the possible hydraulic fracturing phenomenon in the tested rocks. Based on an interpretative model recently developed for HPPTs, a criterion is proposed to determine a proper permeability rate from the HPPT data for design of grout curtains by taking into account the type curves and the transition of flow conditions, and is applied to illustrate the implication of the proposed criterion for the design of impervious barrier in a high arch dam foundation. The proposed criterion could be of significance in the design of impervious barriers for reducing the risk of leakage in rocks under high water pressure condition.

The differences between soil grouting with cement slurry and cement-water glass slurry

Cement slurry and cement-water glass slurry are the most widely applied for soil grouting reinforcement project. The viscosity change of cement slurry is negligible during grouting period and presumed to be time-independent while the viscosity of cement-water glass slurry increases with time quickly and is presumed to be time-dependent. Due to the significantly rheology differences between them, the grouting quality and the increasing characteristics of grouting parameters may be different, such as grouting pressure, grouting surrounding rock pressure, i.e., the change of surrounding rock pressure deduced by grouting pressure. Those are main factors for grouting design. In this paper, a large-scale 3D grouting simulation device was developed to simulate the surrounding curtain grouting for a tunnel. Two series of surrounding curtain grouting experiments under different geo-stress of 100 kPa, 150 kPa and 200 kPa were performed. The overload test on tunnel was performed to evaluate grouting effect of all surrounding curtain grouting experiments. In the present results, before 240 seconds, the grouting pressure increases slowly for both slurries; after 240 seconds the increase rate of grouting pressure for cement-water glass slurry increases quickly while that for cement slurry remains roughly constant. The increasing trend of grouting pressure for cement-water glass is similar to its viscosity. The setting time of cement-water glass slurry obtained from laboratory test is less than that in practical grouting where grout slurry solidifies in soil. The grouting effect of cement-water glass slurry is better than that of cement slurry and the grouting quality decreases with initial pressure.

Comparative Study of Soil Grouting with Cement Slurry and Cement‐Sodium Silicate Slurry

Cement slurry and cement‐sodium silicate slurry are most widely applied for soil grouting reinforcement project. The viscosity change of cement slurry is negligible during grouting period and presumed to be time independent, while the viscosity of cement‐sodium silicate slurry increases with time quickly and is presumed to be time dependent. Due to the significant rheological differences between them, the grouting quality and the increasing characteristics of grouting parameters may be different. Those are main factors for grouting design. In this paper, a large‐scale 3D grouting simulation device was developed to simulate the surrounding curtain grouting for a tunnel. Two series of surrounding curtain grouting experiments under different initial pressures of 100 kPa, 150 kPa, and 200 kPa were performed. The overload test on the tunnel was performed to evaluate the grouting quality of all surrounding curtain grouting experiments. The results show that the increasing trend of grouting pressure for cement‐sodium silicate is similar to its viscosity; the setting time of cement‐sodium silicate slurry obtained from the laboratory test is less than that in the practical grouting environment where grout slurry solidifies in soil; the grouting quality of cement‐sodium silicate slurry is better than cement slurry, and the grouting quality decreases with initial pressure.

Numerical Analysis on Seepage in the deep overburden CFRD

There are many problems in the construction of hydraulic structures on deep overburden because of its complex foundation structure and poor geological condition. Seepage failure is one of the main problems. The Combination of the seepage control system of the face rockfill dam and the deep overburden can effectively control the seepage of construction of the concrete face rockfill dam on the deep overburden. Widely used anti-seepage measures are horizontal blanket, waterproof wall, curtain grouting and so on, but the method, technique and its effect of seepage control still have many problems thus need further study. Due to the above considerations, Three-dimensional seepage field numerical analysis based on practical engineering case is conducted to study the seepage prevention effect under different seepage prevention methods, which is of great significance to the development of dam technology and the development of hydropower resources in China.

Analysis of Causes of Uplift Anomalies in the Čierny Váh Subsoil

The pumped storage hydropower plant of Čierny Váh was created by means of damming up the valley of the Čierny Váh River. The dam is 18.5 m high above terrain and 375 m long in the dam’s crest. Total capacity of the reservoir is 5.1 million m3. Complicated geological conditions in the subsoil of dam’s body – fractured dolomite with local occurrence of tectonic breccia and clays, with the occurrence of intense disturbances - called for the construction of the grouting curtain in the dam’s subsoil. Its depth is about 20 in the area of the riverine plain, and about 60 m in the areas of abutments. During foregoing operations of the structure, more than 30 years, local anomalies in the uplift development in the right abutment’s subsoil of the lower reservoir dam were recorded. Their abnormally high values on the downstream side of grouting curtain have become the subject of extensive discussion and a stimulus for its remediation. To ensure reliable operation of the hydraulic structure a comprehensive analysis of the impact of the long-term operation of the reservoir on the dam safety was carried out. This included an examination of the causes of anomalous development of uplifts using FEM numerical modelling. The paper presents obtained results from this analysis.

Leakage Analysis of Deriner Dam (Artvin-Turkey) Using 3D Modeling

Leakage in engineering structures is considered as one of the main issues. Analysis of the amount of water leakage can be useful in preventing such events. Deriner Dam consists of a concrete arch dam with ancillary structures including tunnels, and an underground powerhouse with an installed capacity of 670 MW. Leakage was observed on the powerhouse after the construction stage. For this purpose, a number of geotechnical data (including rheological and mechanical properties of the grout mixes) were re-assessed to examine the source of leaking. For determination of leakage source, graphics of grout curtain were prepared by using grouting charts with the RockWorks v.16 program. Leakage zones were obtained according to the prepared graphics and showed on 3D model. The results show that temperature variation of grouting mixes is the primary cause of leakage and its effect observed in the underground powerhouse wall of the Deriner Dam.

Towards an optimization design of seepage control: A case study in dam engineering

High dams generally suffer from higher seepage risks in their foundations, and seepage control is an important technology for limiting the amount of leakage and improving the stability of the foundations. In this study, a procedure was proposed for optimization design of seepage control system in large-scale hydropower projects, which relies on sufficient characterization of site conditions and proper quantification of the performance of the seepage control system. The proposed procedure was applied to the design of seepage control system in the Mengdigou Hydropower Station consisting of a double-curvature arch dam 201 m in height. An optimized layout of the seepage control system, including the extended length of grout curtain, the rows of grouting holes and the spacing of drainage holes, was suggested. The proposed procedure provides a guide with lower risk and higher confidence for performance assessment and optimization design of seepage control systems in high dam engineering.

高坝坝基防渗帷幕结构优化研究 Study on Optimization of Anti-Seepage Curtain Structure for High Dam Foundation

针对实际工程坝基防渗处理措施中灌浆帷幕的结构设计，既满足安全性又满足经济性问题，本文基于粒子群算法与有限元方法相结合计算满足约束条件下防渗帷幕的平均深度与等效厚度。以某高坝深厚覆盖层上的混凝土面板堆石坝为案例，首先分析二维模型中无防渗帷幕时坝基渗流场情况，得出无防渗帷幕时坝基透水率相对较高，容易产生渗透破环，因此必须在基岩中进行灌浆以降低坝基渗流量。研究发现：粒子群算法在帷幕结构优化中的可行性和适用性，得出随着迭代次数的增加，粒子不断向最优解靠近，目标函数(工程造价)随着迭代次数的增大逐渐减小并趋于平缓，该研究成果可用于对工程中帷幕灌浆的结构设计提供参考。 The design of grouting curtain in seepage control measures of the dam foundation of the actual project not only meets the safety, but also meets the economic problems. In this paper, based on the combination of particle swarm optimization and finite element method, the average depth and equivalent thickness of impervious curtain under the constraint condition were calculated for concrete face rock fill dam on deep overburden. Firstly, the seepage field of the dam foundation in the 2D model was analyzed, and the permeability of the dam foundation is relatively high when it has no curtain, and it is easy to produce osmotic rupture. It is therefore necessary to perform grouting in the bedrock to reduce dam foundation seepage. The particle swarm optimization (PSO) is feasible and applicable in the optimization of curtain structures. It is concluded that as the number of iterations increases, the particles are close to the optimal solution, and the objective function (engineering cost) is gradually reduced and tends to be gentle as the number of iterations increases. The research results can be used to provide reference for the structural design of curtain grouting in engineering.

Application of the comprehensive forecast system for water-bearing structures in a karst tunnel: a case study

While tunneling in karst terrains, engineers may encounter unpredictable well-developed karst conduits, which frequently lead to water inrush accidents. Geological processes significantly affect the varieties and characteristics of water-bearing structures. Therefore, a comprehensive system for water-bearing structure prediction is first put forward, and then the geological and hydrogeological engineering conditions of the Yuelongmen tunnel in Southwest China are analyzed. To accurately predict the geometric characteristics of water-bearing structures and their spatial relationship with the tunnel face, the transient electromagnetic method (TEM) and ground-penetrating radar (GPR) were comprehensively applied. Then, the induced polarization method (IP) was utilized separately to detect the three-dimensional position and spatial distribution pattern of the water-rich area. According to the comprehensive forecast conclusion, targeted boreholes were drilled, which were selected to verify the water-bearing structure in the survey area. The drilling and detection results matched. Furthermore, the curtain grouting method was adopted for the treatment of the water-rich area. By establishing a comprehensive prediction technology system with the principle of “from qualitative analysis to quantitative identification, from structure locating to the water-bearing structure discrimination, as well as from far and near,” this comprehensive prediction system was successfully put into practice in the karst tunnel in Sichuan; it can play a guiding role in similar projects.