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Study on Hydraulic Fracturing of Filltype Dams During Earthquake

填土坝地震水力压裂研究

基本信息

批准号：
07455194
负责人：
OHNE Yoshio
金额：
$ 1.98万
依托单位：
Aichi Institute of Technology (A.I.T.)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07455194/
关键词：
Filltype Dam Collapse Hydraulic Fracturing Compaction Hydraulic Gradient Effective Vertical Stress FEM Analysis Centrifuge Model Test 浸透圧有効拘束応力遠心載荷アバットメント形状堤体変形

项目摘要

Hydraulic fracturing (Seepage failure) tests were conducted on compacted actual core materials to investigate the relationship between the effective vertical stress sigma_V' and the hydraulic gradient at failure i_f. Results are summarized as follows : (1) sigma_V' has a very close relation to i_f and can be the most effective parameter to explain the phenomenon of Hydraulic Fracturing (H.F.), and (2) the resistance against H.F.depends on the initial degree of saturation of compacted soil.In the centrifuge model tests of investigating the relationship between configuration of abutment foundation and internal deformation of embankment, it is recognized that (1) distribution of the maximum shear strain gamma_<max> depends much on the abutment configuration and large value of gamma_<max> appears in the vicinity of the turning point of foundation slope, and (2) a simple gravity turn-on FEM calculation can be a useful tool to evaluate such mechanical aspects qualitatively.In another centrifuge deformation tests on model rockfill dams, results presented that (1) large value of gamma_<max> appears irrespective of the core width in the upper part of the core and in the vicinity of core trench, and (2) area of low factor of safety against H.F.then concentrates near the core trench.In the centrifuge H.F.model tests on a rockfill dam with a centrally located core, a 27cm high model fill was loaded in 20G and 30G,and settlement and stress distributions in the core were measured by using appropriate transducers. Concluding remarks drawn in the test are as follows : (1) differential settlement and stress redistribution in the core due to the first filling of the reservoir causes reduction in confining pressure in the core, and (2) this directly leads to an internal erosion and associated seepage failure in embankments in a similar manner as observed in actual dams.

对压实的实际岩心材料进行了水力劈裂（渗流破坏）试验，研究了有效垂直应力σ_V'与破坏水力梯度i_f之间的关系。结果表明：（1）σ_V'与i_f关系密切，是解释水力压裂现象的最有效参数;在研究桥台基础形状与路堤内部变形关系的离心模型试验中，认识到：（1）最大剪应变γ_的分布与桥台的<max>形状有很大关系，γ_的大值<max>出现在基础边坡转折点附近，在另一个模型堆石坝离心变形试验中，试验结果表明：（1）在<max>心墙上部和心墙槽附近，无论心墙宽度如何，γ_（max）值都很大，在心墙堆石坝离心高频模型试验中，采用20 G和30 G两种加载方式对高27 cm的模型堆石体进行了加载，并利用合适的传感器测量了心墙的沉降和应力分布。试验得出的结论是：（1）由于水库初次蓄水引起的心墙不均匀沉降和应力重分布，使心墙围压降低，（2）这直接导致了与实际坝相似的内部侵蚀和伴随的渗透破坏。