【作者】 石祥锋；

【导师】 汪稔；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2005， 博士

【摘要】 溶洞顶板稳定性是岩溶区一个重要的工程地质问题,本文以贵州岩溶区某大桥桩基下隐伏溶洞为工程背景,综合研究了溶洞顶板的稳定性。采用有效的评价方法确定了溶洞顶板的安全厚度,突破了规范的规定,并在施工中对溶洞顶板稳定性进行了监测,实践表明这是一种有效的综合研究方法。研究内容主要有:1、溶洞顶板稳定性的影响因素主要有内在因素和外在因素,认为外在因素是引起溶洞顶板稳定性的原因;溶洞顶板稳定性的评价方法已趋向成熟,但是岩溶场地勘察水平已成为实际的制约因素。2、对贵州场地所在区域的碳酸岩岩样进行单轴压缩试验和三轴试验,碳酸岩在力学性质上表现出很好的弹塑性性质;运用比尼奥斯基的工程地质分类法和霍克-布朗的岩体强度准则并结合莫尔-库仑准则对室内试验结果进行研究,获得稳定性评价的工程岩体参数。3、介绍了隐伏溶洞顶板稳定性实体工程,针对实体工程,运用定性、半定量和数值模拟方法进行综合评价,确定桩基下伏溶洞顶板安全厚度大于7.5m。4、改进了钢弦式多点位移计及其安装工艺,成功地应用于施工过程中隐伏溶洞顶板的稳定性监测。分析了监测结果,在现有施工荷载下溶洞顶板处于稳定状态,溶洞顶板岩层的变形都占了总变形量的2/3左右,是变形的主要承担者。5、对实测沉降值和计算值进行了对比,大部分计算值大于实测值,沿钻孔深度计算值和实测值具有相同的沉降趋势,验证了溶洞顶板稳定性评价方法和监测技术的可靠性。更多还原

【Abstract】 The roof stability of karst cave is an important engineering geology problem in karst areas. Based on the engineering of the concealed karst cave under the pile foundation of a bridge in karst areas of Guizhou province, the roof stability of karst cave is studied synthetically. Safe thickness of karst cave roof that break the norm is dissolved by effective evaluation methods and, the roof stability is monitored during construction process. The main original work and results are as follows:1. The factor that influences the roof stability of karst cave mainly contains two kinds, i.e. the intrinsic factor and the exopathic factor. The exopathic factor is the primary one. Recently, many evaluation methods of the roof stability that tend to be perfect have been presented. However, exploration technique to karst site has become the practicable confinement factor to evaluating roof stability of karst cave.2. Uniaxial compression test and triaxial compression test are performed on carbonatite sample in the region of the engineering site. The test results indicate that the elastoplastic mechanical property is exhibited in carbonatite sample. Then, the rock mechanical parameters are obtained by analyzing the test results with Z.T. Bieniawski’s CSIR, Hoek-Brown’s and Mohr-Column’rock strength criterion.3. The engineering of roof stability of concealed karst cave is introduced firstly. Then the safe thickness of the karst cave roof under the pile foundation loading, which is greater than 7.5 meter, is ascertained by qualitative evaluating method and half-quantitative evaluating method and finite element method (FEM).4. The vibrating-wire multipoint-displacement metre and its installation technique are improved, and are successfully used to monitor the roof stability of concealed karst cave during construction. The monitoring results indicate that the displacement of karst cave roof accounts for 2/3 of total displacement and the roof is stable under the existing loading.5. The measured results of settlement are compared with those obtained by FEM. It is shown that the latter is greater than the former and they have the same tendency along the test hole depth. Therefore, the reliability of the evaluating method and monitoring technique of the roof stability of karst cave are validated.更多还原