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1、分类号: P62 1071022251 长 安 大 学硕 士 学 位 论 文黄土边坡强度参数的选取及应用雷晓锋指导教师姓名 钱壮志(教授) 申请学位级别 硕士 学 科 名 称 地质工程 论文提交日期 2005.05 论文答辩日期 2005年 5 月 日 学位授予单位 长安大学 答辩委员会主席： 学位论文评阅人： 2005年 月 日3摘 要强度参数是边坡稳定性计算的重要指标,由于取样和试验过程中对土样的扰动和受力状态的改变,目前通过试验获取强度参数不可缺少但又难以采用，因此选择合理的强度参数是黄土地区边坡工程设计的主要问题。本文通过大量滑坡和极限边坡现场地形的测量资料，将反算强度参数和实验参数进
2、行了对比分析，确定了强度参数的选取原则，并根据选定的强度参数计算给出了黄土边坡设计的基本参数。文章主要进行了以下方面的调查研究工作：1自陕北至关中210国道沿线按自然地理条件和黄土工程性质的差异分为三段。对沿线所有极限边坡测绘了典型断面、老滑坡测绘了地形轮阔，并恢复了老滑坡原地形，原地形也作为极限边坡，绘制出其主断面，为边坡参数的反算提供了地质模型。将极限边坡统计分析，得出各区段的坡高与坡度的相关关系。2在现场测会的同时，在典型边坡和滑坡断面上，采取了原状土样，室内做了常物理力学性质指标测试，并做了在三种不同排水和固结条件下的直剪和三轴试验。对试验数据的统计分析，得出各种土性参数的空间变化规律
3、和试验方式和试验条件对强度参数的影响。总的特点是各段c值的变异性较高，而值的变异性很小，且不同试验方法c值变化大，值变化小。3根据工程上常用的Bishop法，对参数反算模型进行优化。将条分法中的求和优化为积分，推导了求解稳定系数的积分公式，避免人工进行分条的不便。考虑到边坡参数反演时，滑动面也是不确定的，提出了一种最危险滑动面的搜索方法。通过编程实现了稳定性计算和参数反算的功能。计算表明，稳定性计算时，最危险滑动面对应稳定系数极小值；参数反算时，无论是c，还是，最危险滑动面对应的是极大值。4利用本文改进的模型对极限边坡进行反算，认为反算的强度参数是“真值”或接近“真值”。将反算结果与试验结果比
4、较表明：各段直快剪切试验结果与反算结果最为接近，文章采用反算结果对各种试验结果进行了修正；并利用反算参数计算了给定坡高和给定稳定系数的条件下，相应的设计坡度，为边坡设计提供参考。与目前工程采用的方法和参数比较，本文提出的边坡强度参数的选取方法是合理的，参数是基本可信。关键词：黄土； 边坡； 强度； 参数反算； 统计分析AbstractIt is essential in slope stability analysis to get a set of reasonable strength parameters of the soil. Presently, the parameters te
5、sted are generally necessary but difficult to be used in actual engineering. The main problem is disturbing of the samples and changing of the origin stress state in the process of sampling，transporting and testing. By contrastive analysis between strength parameters inversely calculated and paramet
6、ers tested, the author suggests a way of choosing strength parameters, and according to these strength parameters, worKs out the basic parameters of designing loess slope, which is based on abundant local landform surveying data of loess landslide and limit slope. The main achievements of investigat
7、ion and research by author are as follows: 1. From the north to middle of Shanxi Province along 210 highway, according to the diversity of natural and geographical conditions and the loesss engineering characteristics, the survey zone is divided into three sections. The author has surveyed the typic
8、al cross sections of limit slope and the landform outline of old landslide. Original landform of old landslide is recovered, and the main section of recovered slope is also treated as limit slope, which has established geological model for inversely calculating of slope parameters. By large quantity
9、 of statistic analysis of limit slope, the correlative relations between height and gradient of slope in respective sections are elicited.2. While surveying, undisturbed soil samples from typical cross-sections of slope and landslide were also collected and indoor tests have been done to get the ord
10、inary physical and mechanical indexes and direct shear test and tri-axial test under three different drainage and consolidation conditions also been done to get the strength parameters. By statistic analysis to test data, the regularities of spatial change of various soil parameters and the effects
11、that testing methods and testing conditions impact on strength parameters have been elicited. The total characteristic is that the variability of the c value is comparative high, that of the value is very low and under different testing methods, the variability of c value is big, that of the value i
12、s small.3. According to Bishop method genarally used in engineering, parameters inversely calculating model has been optimized. Slice method is optimized to be integral method that avoids the inconvenience of artificial slicing. Considering the uncertainty of sliding surface of slope when inversely
13、calculate the slope parameters, a search method for the most dangerous sliding surface of slope has been elicited. And by programming, the function of stability calculation and parameters inverse calculation has been realized. The calculation results indicate that when calculate stability factor of
14、slope, the most dangerous sliding surface corresponds to the minimal value of stability factor and when inversely calculate the parameters(c or ) of slope, the most dangerous sliding surface corresponds to the maximal value.4. When the improved model in this thesis is used to inversely calculate the
15、 limit slope, the strength parameters of inverse calculation could be considered as “truth value” or near to “truth value”. Comparing the result of inverse calculation and the testing result indicates: the result of direct and fast shear test is nearest to inverse calculation. The inversely calculating result involved in this thesis is used to correct various testing results, and those inversely calculating parameters are used to calculate the corresponding design gradient of slope as given height and s
