国道G318巴塘至拉萨段碎屑斜坡灾害与稳定性分析

Slope disaster and stability analysis of the G318 Highway in the section from Batang to Lhasa

为了有效整治国道G318巴塘至拉萨段沿线碎屑斜坡灾害,保障川藏公路全天候安全畅通,在详细调查该区段公路沿线110个碎屑斜坡后,根据斜坡碎屑物质成分和运动特征等,将其分为溜砂坡、滚石坡和碎石坡,并描述了各类碎屑斜坡的基本特征。利用信息熵分析了斜坡稳定性的主要影响因素,并建立了基于支持向量机的碎屑斜坡稳定性评判模型,模型检验表明其准确率超过86%。结合实地调查和预测结果,对该段公路碎屑斜坡的治理提出了建议。

The paper has made an investigation of 110 slopes along the G318 Highway with its section from Batang to Lhasa for the 3 years so as to effectively control the debris landslide disasters and ensure the safe traffic and transportation of the Sichuan- Tibet Highway. For the said purpose, we have conducted a classification and characteristic description of the road-surface substance particles based on the general survey of the roadway sand particle composition, the particle sizes of such substance and their special movement regularity. As a result of investigation, the main factors affecting the stability of the debris slopes have been identified and determined based on their information entropy with a stability discriminant model for the debris slopes being built by using a supporting vector machine. And, next, we have brought about the following suggestions on how to improve the highway slopes based on the field investigation. The suggestion of the paper can be shown in the following manners ： First of all, the debris slopes should be subdivided into the sand sliding slopes, the rolling stone slopes and the gravel slopes. The correlation degree analysis of the 14 factors affecting the stability of debris slopes has been carried out via the information entropy with the 6 main factors being chosen for the stability evaluation model, including the sand-surface precipitation, the average slope degree and height of the debris mass, the engineering excavation, as well as the vegetation coverage in the order from big to small and from higher to lower. When a stable discriminant model and simulation verification model were established for the assessment, it has been found that the accuracy rates can reach 86.67% and 88.24%, respectively. And, then, further suggestions have been brought about based on the field investigation and model predictions： （1） The protection grades to deal with the surface water spoil to the sand sliding slope in the related highway sections; （2） The efforts to be made to stabilize the rolling stones that may fall to the sliding routes of the highway, or from the exposed parts of the slope ; （3） Opencut tunnels, shed tunnels and other preventive measures that have been taken to the gravel slopes. All the aforementioned measures and steps taken can all be regarded as a strategic reference to guarantee the success of such highway construction.