Land Subsidence Disaster Research Articles

Model test study on the mechanical response of metro tunnel to land subsidence

Land subsidence is a prominent engineering geological problem faced by many cities in the world and poses a serious threat to urban infrastructures. Xi'an is one of the cities in China that has suffered the most serious land subsidence disasters and has thus faced the challenges in its ongoing metro construction. To solve this problem, in this paper we carried out a model test and numerical simulation of metro tunnel that crosses a land subsidence area and analyzed the mechanical response of the tunnel and the deformation and failure characteristics of the lining. The results show that the tunnel exhibits downward flexural deformation in the middle, slight warpage on both ends in the longitudinal direction, and local torsion in the horizontal direction in the presence of land subsidence, the maximum deformation of the ground surface is about 80% of the tunnel deformation. Furthermore, the vault and inverted arch are in opposite tension–compression states, and the lining stress decreases inside the subsidence area but increases outside it. When the actual subsidence reaches 225 cm, the metro tunnel crossing the edge of the land subsidence area has failed. We find that the deformation and failure of metro tunnel crossing land subsidence area is a combination mode of flexural tension–compression and local torsion, which affects 2.5 times the length of the intersection between the tunnel and the subsidence area. Also, some countermeasures and suggestions are proposed to deal with the adverse impacts of land subsidence on metro tunnels.

LAND SUBSIDENCE AND GEOTECHNICAL IMPACT OF JAKARTA KOTA AREA

Land subsidence has long occurred around the Special Capital Region of Jakarta. It is important to know and deal with Land subsidence events which also cause various negative impacts. Aim: When large amounts of groundwater are withdrawn from certain types of rocks, such as fine-grained sediments, land subsidence occurs. The rock compacts because the water helps to keep the ground in place. When the water is removed, the rocks collapse in on themselves.The immediate impact is the building collapse around the Kota Tua of DKI Jakarta. Methodology and Results: The research method used is a quantitative descriptive survey method by observing the amount of land subsidence that occurs in the Kota Tua area and its surroundings. The results showed that there has been a vertical land subsidence that varies between 20-60 cm. Based on the results of the resistivity values and coordinates plotted on the Regional Geological Map (Jakarta and Kep Seribu), the research location is classified into Lithology: Clay, Sand Silt, Gravel, and Pebbles (Quartenary deposits). The phenomenon, land subsidence, is caused by a combination of various parameters, including natural consolidation of alluvial soils, excessive groundwater extraction, and also building loads from infrastructure development and tectonic factors. Conclusion, significance, and impact study: Knowing the value of land subsidence and its location is expected to support urban planning, basic infrastructure planning and development, housing, settlement planning, and local financial improvement in efforts to mitigate land subsidence disasters.

Study on Microstructure and Silting Characteristics of Soft Soil: A Case Study of Nansha District, Guangzhou

With the development of society and economy, land subsidence in soft soil areas has become a prominent geological disaster in our country’s coastal area. Land subsidence has the characteristics of irreversibility, wide influence range, long aging, etc., and these characteristics are closely related to the characteristics of soft soil, such as physical and mechanical parameters, microstructure characteristics, etc. The Nansha District of Guangzhou was taken as the study area in this paper. Through the collection of preliminary data, two-dimensional scanning electron microscopy, and three-dimensional Computed Tomography (CT), the micro-structure characteristics of soft soil are expounded and its plugging characteristics are further analyzed. The results show that the study area’s soft soil has a honeycomb, granular, and flocculent structure. From the perspective of pore scale distribution, the number of macropores and ultramicro pores is small, and the continuity is poor. In most small and medium pores, namely the aggregate and granular pores. The siltation of soft soil is closely related to the microstructure of soil and can be treated according to the effect of siltation characteristics on the consolidation settlement of soft soil. The research results of this paper can provide targeted prevention and control suggestions for the soft land subsidence disaster in the Nansha area, and also provide a reference for other similar research.

Susceptibility Analysis of Land Subsidence along the Transmission Line in the Salt Lake Area Based on Remote Sensing Interpretation

As the influence of extreme climate and human engineering activities intensifies, land subsidence frequently occurs in the Salt Lake area of Qinghai Province, China, which seriously threatens the stability of the UHV transmission line crossing the area. Current susceptibility analyses of land subsidence disasters have mostly focused on the classification of land subsidence susceptibility and have ignored the differentiation of susceptibility among different land subsidence intensities. Therefore, the land subsidence susceptibility map does not meet the operation and maintenance management needs of the UHV transmission line, let alone planning and designing of new lines in the Salt Lake area. Therefore, in this study, we proposed a susceptibility analysis of different land subsidence intensities along the transmission line in the Salt Lake area. The small baseline integrated aperture radar interferometry (SBAS-InSAR) method was used to obtain the land subsidence along the transmission line based on 67 Sentinel-1 remote sensing interpretation datasets from 2017 to 2021. Based on a combination of K-means clustering and the transmission line specifications, four annual land subsidence intensity grades were identified as 0~−2 mm/year, −2~−10 mm/year, −10~−20 mm/year, and <−20 mm/year. In addition, eight geological environmental factors were analyzed, and a multi-layer perceptron neural network (MLPNN) model was used to calculate the susceptibility of the different land subsidence intensities. The area under the curve (AUC) and practical examples were used to verify the reliability of the different land subsidence intensities susceptibility mapping. The AUC values of the four subsidence intensity grades showed that the results were accurate: the <−20 mm/year grade produced the largest AUC (0.951), with the −10~−20 mm/year, −2~−10 mm/year and 0~−2 mm/year grades producing AUCs of 0.926, 0.812, 0.879, respectively. At the same time, the susceptibility classification results of different land subsidence intensities were consistent with the interpretation and site tower deformation. The results of this study provided the distribution of land subsidence susceptibility along the transmission line, distinguished the susceptibility of different land subsidence intensities, and provided more detailed subsidence information for each transmission tower. The results provide important information for transmission line tower planning, design, protection, and operation management.

A Review Disaster Mitigation of Jakarta Land Subsidence Areas

The Jakarta Capital Special Region of Jakarta is an area in the Java Island that has the highest level of vulnerability to land subsidence disasters. Land subsidence is caused by several factors such as excessive use of groundwater and natural compression of soil conditions. This study used a review analysis method based on a literature study on mitigation of land subsidence disasters in Jakarta city. The mitigation planning of land subsidence disasters in Jakarta will refer to government regulations on disaster management and Jakarta City spatial planning. Disaster mitigation is necessary to anticipate or reduce disaster risk. Disaster mitigation is a series of efforts to reduce disaster risk through physical development combined with awareness and capacity building in dealing with disaster threats. Education cannot be separated from the active role of the community and local government. High-densely populated areas will lead to more use of groundwater in Jakarta city. The excessive use of groundwater has resulted in more intensive land subsidence in Jakarta’s urban area. The safe zone mapping of subsidence disasters is prominent to reduce and control land subsidence disasters. The government’s efforts to lessen the impacts of land subsidence are by educating the population in disaster areas.

Monitoring and analysis of land subsidence in modern Yellow River Delta using SBAS-InSAR Technology

Modern Yellow River Delta has become one of the areas with serious land subsidence disaster in the plain area of Shandong Province. In this paper, Small Baseline Subsets - Interferometry Synthetic Aperture Radar (SBAS-InSAR) technology was used to process the Sentinel-1A data from August 2018 to October 2019 in the modern Yellow River Delta, in order to obtain the range and rate of land subsidence in the study area. At the same time, use the Leveling results of the same period to verify the accuracy. By selecting four larger land subsidence rate as feature points to analyze the characteristics of surface time series deformation, the influencing factors of land subsidence in this area are found out. The results show that during the past 2018-2019 years, the land subsidence in the the Yellow River Delta area was mainly distributed in Xianhe Town, southern the Huanghekou Town, Hubin Town, Guangrao County and its surrounding areas, DaWang Town, Yingli Town, Yangkou Town and the western part of Binhai Township, the most serious subsidence area is located in Xianhe Town, with an annual settlement rate of -204.7 mm/a. The land subsidence in the Yellow River Delta is mainly affected by groundwater overdraft, and the distribution characteristics of land subsidence funnel and deep groundwater depression funnel are basically consistent. In addition, natural factors such as consolidation of Quaternary loose sediments and regional tectonic movement also exacerbate the occurrence of land subsidence.

Integrated management of groundwater exploitation and recharge in Shanghai based on land subsidence control

Abstract. Shanghai has a long history of exploitation and utilization of groundwater in order to meet the needs of industrial production and residential water. As a result, serious land subsidence disasters were induced. Land subsidence poses a huge security threat to the low-altitude coastal city of Shanghai. The development of land subsidence in Shanghai is closely related to the exploitation of underground water. In order to control land subsidence disasters, Shanghai has taken three key measures, i.e., the amount of compressed groundwater exploitation, the adjustment of groundwater exploitation level, and the implementation of artificial groundwater recharge, which have become the most effective measures for land subsidence control. However, as the groundwater levels of various aquifers in the region rise sharply, land subsidence is effectively controlled, and the measures of groundwater exploitation and recharge need to be dynamically adjusted to adapt to the current situation. In this context, from the perspective of history, the paper analyzes the long-term groundwater exploitation and recharge process and the development characteristics of land subsidence in Shanghai and studies the evolution process of land subsidence in different stages. From the perspective of land subsidence prevention and control, the paper analyzes the management measures of groundwater exploitation and recharge and the great achievements. The research results can provide a basis for land subsidence control and comprehensive groundwater management in the new period and can also provide a demonstration and reference for groundwater resource management in similar areas.

LAND SUBSIDENCE STUDY IN KENDAL DISTRICT, CENTER JAVA

The need for information about disaster prone areas in Indonesia began to be felt very urgently since the natural disasters that occurred in many places in Indonesia. One of the information needed is information related to the area of land subsidence disaster. Kendal Regency is one of the areas located along the north coast of Java which is generally composed of alluvium deposits that have not been maximally consolidated, so they have high soil compressibility. These conditions indicate that compaction of the land naturally is still ongoing, so that if there is excessive overloading it will lead to a process of land subsidence regionally. By knowing the value of land subsidence and the areas that experience it, it is expected to be able to support regional planning, planning and development of basic infrastructure / facilities, housing / settlement planning as well as regional economic development in efforts to mitigate land subsidence.

Inversion and Prediction of Consolidation Settlement Characteristics of the Fluvial Sediments Based on Void Ratio Variation in the Northern Modern Yellow River Subaqueous Delta, China

The modern Yellow River delta is formed near the estuary of the Yellow River with the characteristics of short formation time, efficient sedimentation rate and loose structure which make sediments prone to be compacted and consolidate under the geostatic stress and overburden stress. It is one of the key areas with land subsidence disasters in China, bringing a series of safety hazards to production and living. Based on the data of massive surface cores and ten drill holes ranging from 12 to 40 m obtained from the northern modern Yellow River subaqueous delta, the inversion method suitable for the calculation of consolidation settlement characteristics of the modern Yellow River subaqueous delta is discussed, and the consolidation settlement characteristics of the delta sediments are inversed and predicted in this paper. The actual void ratio of the delta sediments at the depth from 3 to 15 m shows a significant power function relationship with the depth, while the void ratio of the sediments below 15 m changes little with depth. The pre-consolidation settlement (from deposition to sampling) of the delta sediments is between 0.91 and 1.96 m, while the consolidation settlement of unit depth is between 9.6 and 14.0 cm m−1. The post-consolidation settlement (from sampling to stable) of the subaqueous delta sediments is between 0.65 and 1.56 m in the later stage, and the consolidation settlement of unit depth is between 7.6 and 13.1 cm m−1 under the overburden stress. The delta sediments with a buried depth of 3 to 7 m contribute the most to the possible consolidation settlement in the later stage.

THE MONITORING AND SPATIAL-TEMPORAL EVOLUTION CHARACTERISTIC ANALYSIS FOR LAND SUBSIDENCE IN BEIJING

Abstract. At present the land subsidence has been the main geological disaster in the plain area of China, and became one of the most serious disaster that restrict the social and economic sustainable development, it also is an important content in the project of national geographic conditions monitoring. With the development of economy and society, Beijing as the capital of China has experienced significant population growth in the last few decades which led to over-exploitation of the ground water to meet the water demand of more than 20 million inhabitants, especially in the urban region with high population density. However, the rainfall and surface runoff can’t satisfy the need of aquifer recharge that product the land subsidence. As China’s political center and a metropolis, there are a lot of large constructions, underground traffic projects and complicated municipal pipeline network, and Beijing is also an important traffic hub for national railway and highway network, all of them would be threatened by the land subsidence disaster. In this article the author used twenty ENVISAT Synthetic Aperture Radar (SAR) images acquired in 2008 June–2010 August and ten TerraSAR images acquired in 2011 June–2012 September were processed with Small Baseline Subset SAR Interferometry (SBAS-InSAR) techniques, to investigate spatial and temporal patterns of land subsidence in the urban area of Beijing.

Population condition analysis of Jakarta land deformation area

Jakarta is located in the North West area of West Java Province which geographically positioned on 106°33’00”-107°00’00”BT and 5°48’30”-6°24’00”LS. Land subsidence has occured in several types of landuse such as trade, industrial and settlement area of the urban area of Jakarta. The land subsidence disaster is one of the consequences of building and road construction in Jakarta. This is caused by massive groundwater utilization and failure in landuse planning. This study aim to analyze the population density and settlement pattern in the urban area of Jakarta which the occurence of land subsidence has been detected. It is important to understand landuse and settlement planning processes in the area which land subsidence occured. Detection of land subsidence distribution become a necessary parameter in landuse planning. While the land subsidence area detected using Differential Synthetic Aperture Radar (DInSAR) method. The result shows the area which land subsidence occured has a very high population density and clustered and linear settlement pattern. This area is mainly used as industrial, trade, and settlement.

Model test of soil deformation response to draining-recharging conditions based on DFOS

Intense groundwater exploitation and seasonal fluctuations of water level in phreatic aquifer cause land subsidence disasters. To better understand the land subsidence mechanism caused by groundwater withdrawal, a small-scale sand-clay interbedded model box was built to carry out consolidation and rebound tests during two drainage-recharge cycles. Distributed fiber optical sensing (DFOS) technologies were introduced for coupled monitoring of soil strain and water content to analyze response characteristics of each layer to water level changes. The results indicate that soil layers were compressed during drainage and rebound during recharge, with clay layer deformation more obvious than sand layer deformation. Deformation of the sand layer was synchronous with water content changes, while that of the clay layer lagged behind water content changes due to its lower permeability coefficient. The segmented compression clay layer curve shows that the water content rapidly decreased when it was lower than the liquid limit, while the clay layer compression rate obviously accelerated during drainage. When the water content was higher than that of the liquid limit during recharge, the rebound rate significantly increased. Under the condition of repeated drainage and recharge, the soil microstructure changed with decreasing porosity and permeability coefficient, leading to a longer consolidation time. With increasing cycling times, the soil gradually tended toward elastic deformation. The observations propose a novel technology, DFOS technology, for monitoring land subsidence caused by seasonal water level fluctuations and dewatering projects. The test results are of great significance to investigate land subsidence mechanisms and evaluate soil layer compression potential.

Conceptual Framework for the Development of an Indicator System for the Assessment of Regional Land Subsidence Disaster Vulnerability

This paper aims to develop a set of valid and reliable indicators to evaluate the regional land subsidence disaster vulnerability. The proposed indicator system can provide effective theoretical support for further land subsidence risk evaluation and risk management. This study transfers the qualitative analysis of land subsidence vulnerability to quantitative evaluation by developing a universal land subsidence vulnerability indicator system and outlining a corresponding vulnerability analysis framework. The land subsidence vulnerability analysis in Xixi-Chengnan area, Jiangsu Province, China used as the case study to prove the applicability and the simplified use of the proposed system. Based on the flexibility of the proposed universal indicator system, indicators can be added into and deleted from the system, according to the actual situation in a certain study area.

Risk evaluation of land subsidence and its application to metro safety operation in Shanghai

Abstract. Based on sufficiently investigating characteristics and risk connotation of land subsidence, a risk evaluation index system for land subsidence disaster is established, which is combined with the sensitivity feature of the hazard bearing body to land subsidence. An appropriate evaluation method system is established by using an improved fuzzy analytic hierarchy process method. So risk evaluation is developed for providing theoretical basis and technical support for the regional management of land subsidence prevention and control. On this basis, as a case of Shanghai metro, firstly, the paper studies the identifying risk sources of the metro. According to metro linear characteristics, external indexes of representing subsidence risk are obtained. Studying the subsidence risk of the metro, relevant achievement has provided the technical basis for daily main monitoring, early warning and work arrangement.

The interaction between land subsidence and urban development in China

Abstract. The Yangtze River Delta and North China Plain are experiencing serious land subsidence development and are also the areas that have undergone the fastest urbanization. Rapid urban development inevitably requires more water resources. However, China is a country with small per capita water resources, nonuniform distribution of water resources, and over-exploitation of groundwater – all of which are critical factors contributing to the potential for a land subsidence disaster. In addition, land subsidence has brought about elevation loss, damaged buildings, decreased safety of rail transit projects, lowered land value, and other huge economic losses and potential safety hazards in China. In this paper, Beijing, a typical northern Chinese city deficient in water, is taken as an example to explore (a) the problems of urban development, utilization of water resources, and land subsidence development; (b) the harm and influence of land subsidence hazards on urban construction; and (c) the relationship between urban development and land subsidence. Based on the results, the author has predicted the trend of urban development and land subsidence in Beijing and puts forward her viewpoints and suggestions.

Coupled Numerical Simulation Research on Dewatering and Land Subsidence in Deep Foundation Pit

With the construction of deep and large foundation pit, land subsidence disasters caused by dewatering in deep foundation pit become very serious. Using the coupled model of foundation pit dewatering and land subsidence and putting it into foundation pit dewatering construction, analyzes and summarizes the effect of land subsidence in space and time, which will provide references for the design and construction of foundation pit dewatering.

Vulnerability Assessment of Land Subsidence Induced by Groundwater Overexploitation — A Case of Xixi-Chengnan Area in Jiangsu Province

This research takes the land subsidence in Xixi-Chengnan area, Jiangsu province as a case study, quantifies the relative land subsidence vulnerability in terms of vulnerability degree and determines the numerical classification of vulnerability level at the township scale based on the constructed subsidence vulnerability assessment framework, and the detail analysis of natural geographical environment and regional socio-economic conditions in the study area. The vulnerability assessment process is quantitative, objective and comprehensive, provides effective information for the systematic study of land subsidence in Xixi-Chengnan area, lays the foundation for planning of regional land subsidence disaster prevention and reduction, and is worthy of learning for the whole Su-Xi-Chang area and even other subsidence areas.

The Study of Land Subsidence Disaster Prevention by Water Resource Exploitation and Groundwater Recharge — A Case of Changhua and Yunlin Regions, Taiwan

The Study of Land Subsidence Disaster Prevention by Water Resource Exploitation and Groundwater Recharge — A Case of Changhua and Yunlin Regions, Taiwan

Land subsidence in Tianjin, China

Land subsidence has been affecting Tianjin for the past 50 years. It leads to comprehensive detrimental effects on society, the economy and natural environment. Overpumping of groundwater is the main cause. In 2008, the maximum cumulative subsidence reached 3.22 m and the total affected area nearly 8,000 km2. The subsidence reached its most critical state in the early 1980s when it occurred at a rate as high as 110 mm/year. At the same time, groundwater extraction had also reached a maximum of 1,200 million m3. By importing the Luan River to Tianjin and restricting exploitation of groundwater, hydraulic heads gradually recovered after 1986 in all aquifers, and this has continued to the present in the second aquifer. The subsidence rate in urban areas dropped to 10–15 mm/year. The area of groundwater extraction expanded to the suburban area with economic growth in the 1990s, and it was shifted to the third and fourth aquifers. At present, with a subsidence rate of 30–40 mm/year, four new suburban subsidence centers have been formed. Several measures were adopted to mitigate and prevent land subsidence disasters. These included restricting groundwater exploitation, groundwater injection, prohibiting use in the specific zone, a pricing policy for water resources, advocating water-saving technology, and strict enforcement of groundwater laws. Although the subsidence area is still increasing slowly, the subsidence rate is being controlled.

Land Subsidence Disaster Survey and Its Economic Loss Assessment in Tianjin, China

Land subsidence is a kind of widespread geological disaster that occurs in China’s coastal cities. The Tianjin metropolis has suffered negative influence of land subsidence since the 1950s. Land subsidence disaster scenarios were field surveyed and done with archival research using a variety of sources to document the historical record of the disaster, with the results showing land subsidence lead comprehensive detrimental effects on society, economy, and the natural environment. The economic loss was assessed and evaluated in urban infrastructure, building, conservancy engineering, environmental loss, secondary disaster, etc., with help of various methods, such as historical data statistics, expert judgment, shadow project calculation, modeling techniques, etc. The outcome of economic loss is about RMB135.6 billion (US$18.03 billion) up to 2007. This result, although undoubtedly incomplete, subjective, and selective, provides a believable support for the administration’s decision making toward the implem...