Experimental Study On Temporal And Spatial Characteristics Of Ground Fissures Considering Basement Relief

With the development of the national economy, groundwater resources have been over-exploitation in many areas of our country which led to serious land settlement. The uneven settlement induced a lot of ground fissures, resulting in serious environmental problem and great loss of economic. Therefore, it has very important scientific value and practical significance to carry out the study on three-dimensional geological structure of uneven settlement and ground fissures.Based on the ground fissures in Suxichang area, experimental studies on characteristics of ground fissures evolution which were caused by uneven settlement of thick uneven soft clay under the background of basement and fracture structure were carried out. The analysis on the dynamic process of ground fissures development has been carried out through information monitoring such as electric potential, current, apparent resistivity, seepage and deformation and so on.Ground fissures of Guangming village, Xibei town is located in the junction of new China second uplift and Q inling Mountains east-west tectonic belt. There are multiple parallel uplift structures tilted from south to north and the fluctuation of basement is volatile. The field geological investigation and indoor analysis show that ground fissures mainly develop in the area of bedrock uplift and the larger fluctuation area, and the basal structure has obvious controlling effect on the formation and evolution of the ground fissures.The soil desiccation cracking tests based on considering buried hill and fluctuation in the basement indicate that: the cracking progress can be divided to pre-cracking, rapid cracking and cracking stagnation three stages. Cracking evolution is influenced by model boundary and buried hill and fluctuation in the basement. In the fast cracking stage II-1, cracks are mainly developed in the model boundary while in stage II-2, cracks are mainly developed in the influence scope of basement. In the stage III, the overall pattern of cracks has no t changed significantly although the surface cracking is still happening. The later cracks were approximately perpendicular to the early cracks, especially in the zone of basement and model boundary. Based on NDPGES, we analyzed the inversion of the dynamic process of soil cracking, the results shows that the analysis results anastomosed the observed results.The test of ground fissures induced by uneven settlement of soil was carried out under the geological condition of Guangming village, Xibei town, Wuxi Province. Based on the geoelectric response characteristics in different parts of the soil(electric potential, excitation potential, excitation current and apparent resistivity) and the analysis of soil surface settlement monitoring, this paper analyzes the characteristics of uneven settlement and ground fissures evolution and achieves the following understanding: The change of electric potential, current and resistivity in soil is closely related with water content, along with the change of water content in soil, electric potential, excitation potential, excitation current and apparent resistivity change sharply. Uneven settlement leads to cracks in soil, N DPGES inversion information and settlement observation show that it is easy to induce uneven settlement and cracks in the position of larger curve curvature. The greater the degree of uneven settlement, the greater cracks length, width and depth will be.