【作者】 蔡江东；

【导师】 姜振泉；

【作者基本信息】 中国矿业大学 ， 地质工程， 2009， 博士

【摘要】 自然地质作用和人类工程活动不但导致了多种类型的地质灾害,同时也会在地表引起了复杂的环境岩土工程问题。如深层构造蠕动,地下固体矿产及地下水、地下油气资源的开采,地下隧道盾构施工,深大基坑降水、开挖等引起的深部地质条件扰动在引发产生地表塌陷、开裂和地面沉降等地质灾害效应的同时,也会导致较大范围内的地表场地土工损伤问题。通过对地裂缝场地及受采动塌陷影响场地的实践经验总结,本文提出了“深层扰动场地”的概念,对此类场地土——“结构扰动土”的力学性状和主要工程问题作出了概要分析,并结合大屯煤电公司徐庄矿塌陷区外围迁建场地变形及建筑物开裂的工程实例,重点就扰动土的结构力学特征及其细观识别方法、扰动场地变形场及承载性状等问题进行初步研究,取得了一些重要发现和认识。(1)土的结构扰动能够导致土的物理力学性质指标的细观差异。初步分析发现,饱和度指标对结构扰动土的指示作用有较高的灵敏性。模型试验表明,土样的饱和度指标,特别是试样的透水或真空透水饱和度指标,因遭受扰动程度不同在场地的分布上显现出空间效应——随离扰动源距离的增加,饱和度指标逐渐减少;研究还发现,饱和试验中,结构扰动或损伤土存在不止一次的吸水过程。(2)场地土的扰动程度因其距离扰动源的空间距离不同而使静力触探数据在结构、层次上存在差异,借助非线性动力学理论中配分函数可以验证这种差异的存在;而重标极差理论中赫斯特指数表明,扰动在空间上有持续性和继承性特点;通过分形维和多重分形谱可以进一步描述静力触探数据的空间变化特点。(3)基于数字图像相关技术,获得扰动土体的受载位移场的基本特点。与弹性半空间原状地基不同,轴心荷载作用下,结构扰动场地地基土发生不对称变形,临近扰动源一侧的土体有显著的侧向位移,而地基的破坏形式也发生相应的变化。(4)根据结构扰动场地土的性质特点,建立了弹性半无限空间地基损伤模型,从理论角度分析了结构扰动场地地基土的承载强度。更多还原

【Abstract】 Natural geologic action and human engineering activity are not only rebuilt many kinds of the geologic disaster, but also leads to the complicated environmental geotechnical problems in the earth’s surface. Natural geologic action and human engineering activity such as deep structure peristalsis, mining the underground solid mineral, extraction of groundwater, the exploitation of underground oil and gas resources, underground shield tunneling construction, the deep department geologic condition perturbation which are caused by dewatering and excavate of deeply foundation pit bring collapse and craze of earth’s surface and ground sedimentation geologic disasters effect in the meantime, also cause the ground soil and engineering damnify problems of the earth’s surface in the great scope.Based on the summary of the practice in the ground fissure site and mining goaf field, the paper put forward the concept of depth disturbance site and studied the physico-michanical property of structure-disturbed soil. At the same time, the major engineering problems had been discussed. Combining with the engineering example in Datum mine area, we mainly study the property feature of structure-disturbed soil and the meso- identification method; also we discussed the deformation behavior and bearing capacity of the site and drew some important cognition as followed:(1)Disturbance of soil structure may leads to the change of physical indices of soil in meso-way. Pilot study had shown that saturate degree is more sensitive to the change than other indices. Model experiment indicated that saturate degree especially submerged in water changed evidently as the sampling position varied, the further study found that saturate degree has the trend of less as the sampling position became more away from the‘mine goaf’. Furthermore, there existed more than once drink process when the structure-disturbed soil is in water immersion.(2)The datum of static cone penetrate test (CPT) curve has hierarchical feature. The difference of the datum will be shown as the prospecting hole become more far away from the mine goaf. With the aid of partition functions, we may validate the situation. R/S analysis also indicated that the disturbance caused by mining activities has the property of inherence and sustainability. We may make a further cognition of the characteristic of spatial variation of CPT datum by using fractal and multi-fractal theory.(3)In order to find the stress diffuseness feature in the structure-disturbed site, we designed a simulation test. With the help of digital-image correlation technology, we discovered the displacement field of the structure-disturbed site under the axes load. Difference from the distortion in the semi-infinity elasticity space, the damage of the subgrade in structure-disturbed site has the characteristics of asymmetry, there exist notable lateral deformation near the exhausted area. Result also show that the failure model of the foundation was changed.(4)Based on the understanding of the property of structure-disturbed soil, we established the subgrade destroy model which is on the basis of semi-infinity elasticity space. Formulae of calculating the ultimate bearing capacity of the foundation in structure-disturbed site have been derived, also we illustrate engineering example to validate the result.更多还原