贺兰口岩画载体落石危害及治理研究

CAUSE AND PREVENTION OF ROCKFALL DISASTER FOR ROCK PAINTINGS IN HELANKOU

因暴雨、地震和岩羊踩踏等不确定因素,贺兰口沟口至"水关"处发育的34处孤石极易失稳滚落形成落石对岩画和游人安全构成严重威胁。通过对34处孤石数量、成因、分布、岩性和几何特征全面调查与分析的基础上,运用Rocfall软件分析其失稳后的运动过程和能量变化进行分析,得出如下结论:(1)薄层状变质砂岩风化内凹的临空面、岩层层面与两组节理组合切割巨厚层砂岩失稳后堆积于坡面;(2)将落石划分为基岩裸露型、孤石带型和坡面泥石流型3种不同类型;(3)数值模拟结果显示,失稳后弹跳落点有52%~95%的概率在岩画赋存区,所具有能量为301~8412 k J;最终落点有51%~95%的概率在游客栈道,所具有能量为299~7698 k J;(4)监测结果表明,水剂比为0.32、平行布孔、间排距20 cm和抵抗线20 cm布置方案为最优,静态破碎结合人工搬运为岩画保护区落石源头治理的最佳方案。为贺兰口岩画保护区落石灾害的源头治理提供了新的途径与参考。

Collapse is the most devastating disaster in natural landscape scenic spot.There are 34 potential rockfalls distributed in different positions of Helankou.All potential rockfalls pose a serious threat to rock paintings and tourists.Firstly,we comprehensively investigated the genesis,distribution,lithology and geometric characteristics of the 34 potential rockfalls.Secondly,we used the rockfall to analyze the movement process and energy change of the rockfalls.And then we found that there was a high probability that the falling points of the rockfalls can be the rock painting area and the tourist boardwalk.So we decided to use manual cleaning methods to clean up the potential rockfall,because mechanical and blast cleaning could cause irreparable damage to rock paintings.For the large-volume rock,it was better to crush by static crushing agent first.Finally,we did the rock crushing experiment to select the optimal arrangement of static crushing agent.We had the following conclusions.(1)The reasons for the formation of the potential rockfall are the concave of thin-layer,the rock layer level,and the two sets of joints to cut the thick-layer metasandstone.(2)The rockfalls can be divided into three different types:bedrock exposed,solitary belt,and debris flow gully.(3)It is very likely that the falling rocks can fall in the rock paintings area and destroy the rock paintings.(2)The best solution for the control of rockfall is static crushing combined with manual handling.And there is an optimal arrangement of static crushing agent.In short,our study can provide a new way and reference for the prevention of the rockfall disaster in Helankou Rock Painting.