【作者】 张文煊；

【导师】 李永池；

【作者基本信息】 中国科学技术大学 ， 工程力学， 2008， 博士

【摘要】 在水利水电建设工程中,随着越来越多的大中型水电站在高山峡谷地区修建,大型地下厂房的安全、经济、快速施工越发显得重要。而现代水电工程地下厂房的主要施工方式还是钻爆法,爆破振动与围岩应力卸荷的耦合作用可能导致边墙围岩变形增加,应力松驰。同时,爆破振动也可能对新喷射混凝土、岩锚梁造成不利影响,而且爆破开挖本身就会损伤保留岩体。爆破开挖引起的爆破振动、围岩卸荷以及爆破本身对保留岩体的损伤作用对地下厂房施工期及运行期的安全有着重要影响,因此研究大型地下厂房开挖爆破振动的破坏特性具有重要意义。本文结合龙滩、东风水电站施工,从理论、试验、数值模拟以及现场观测等研究了大型地下厂房开挖爆破振动的破坏特征。首先分析了大型地下厂房的开挖程序及爆破施工过程中存在的相关问题;然后利用有限元程序计算了爆破振动及动态开挖荷载作用时厂房高边墙和岩锚吊车梁的动力响应;再根据爆破振动的动态及静态实测资料,分析了爆破振动及动态开挖荷载对厂房高边墙、岩锚吊车梁以及岩体内部应力和位移的影响;研究了地下厂房开挖爆破损伤范围;最后提出了地下厂房施工的爆破安全控制标准、振动效应控制的工程措施及开挖优化程序。通过本文的研究,取得了如下主要研究成果:（1）基于动力有限元数值模拟及利用经验公式分析实测数据等方法,研究确定了地下厂房高边墙质点振动速度的分布特性。表明地下厂房开挖过程中,岩石高边墙上的质点峰值振动速度不存在明显的高程放大效应,可以采用经验公式形式v=Kρ^αe^βH用于主厂房边墙及岩锚梁的爆破振动控制和预报。（2）研究了爆破荷载及开挖卸荷荷载对围岩的影响规律,得出了“爆破荷载作用只是在近区影响较大,而在中远区,其影响要小于数值相当的初始地应力动态卸荷的影响;离开开挖轮廓一定距离后,初始应力动态卸荷的影响是引起岩体破坏的主要因素”的结论。（3）研究了岩锚梁的爆破振动响应,分析了相关的实测资料,确定了爆破振动下岩锚梁的响应特点,提出了岩锚梁的爆破安全控制标准。爆破振动作用下,岩锚梁与围岩的结合面是整个岩锚梁结构中的薄弱环节。爆破振动可能造成岩锚梁的锚杆锚固力降低,岩锚梁梁体混凝土强度下降,梁体开裂,混凝土与岩石间粘结面的粘结力损失甚至拉裂。岩锚梁与岩体结合面上水平向最大拉应力出现在岩锚梁与围岩结合面的顶部;而竖直向最大拉应力则一般出现在岩锚梁与围岩结合面的顶部或底部。对于龄期大于28天的岩锚梁,本文首次提出了可以采用7cm/s的质点振动速度作为其爆破安全控制标准。（4）提出了基于质点峰值振动速度安全判据及最大拉应力准则预测爆破开挖损伤范围的方法,确定了爆破开挖损伤范围。保护层的扩挖爆破是引起边墙爆破损伤的主要原因,在保护层扩挖爆破中,宜采用较大的装药不耦合系数。爆破损伤范围一般限制在保留岩体的表层;对光面爆破,其爆破损伤范围约为10倍孔径量级。更多还原

【Abstract】 In the hydroelectric engineering construction, with more and more medium and large size hydraulic powerstation built in high mountain canyon district, the safety, economy and quick construction of large underground powerhouse seem to be more and more important. Drilling and blasting are still the main methods in modern underground powerhouse excavation. The coupling of blasting vibration and surrounding rock stress may result in the increase of surrounding rock deformation and relaxation of stress. Moreover, the blasting vibration may do harm to the latest shotcrete, rock-anchored beam, and the blasting excavation itself may damage the remaining rock mass. The blasting vibration and its damage effect to the remaining rock mass will have big influence on the safety of underground powerhouse construction and function. So the study of large underground powerhouse’ damage characteristic under blasting vibration is important.Basing on the construction of Longtan and Dongfeng hydraulic powerstation, several methods such as the theories, the experiment, the number simulation and the field observation are used to study the damage characteristic of underground powerhouse under blasting vibration. Firstly, the construction procedure and characteristics of the large underground powerhouse are analyzed. Then with finite element program, the vibration respondence of underground powerhouse under blasting vibration is simulated. And then the blasting vibration attenuation rule and the blasting vibration effect to surrounding rock, to shotcrete ,to rock-anchored beams are studied. Moreover, the damage range of the blasting to remaining rock mass was analyzed. Finally, the blasting vibration control criterion of underground powerhouse is proposed. Through the study of the paper, several conclusions are drawn as follow:（1） Based on the method of dynamic FEM numeric simulation and the analyzed of the practical data, the distribution feature of particle vibration velocity along high sidewall is determined. The research indicates that the magnifying effect of particle peak vibration velocity along the high sidewall in underground excavation is not obvious. The empirical formula v = Kρ^αe^βH can be used to control and forecast the blasting vibration of the sidewall and the rock-anchored beams.（2） The infection of the blasting loads and excavation unloading loads to surrounding rock is studied, a conclusion was draw that the blasting loads which just have greater effect on the area close to the work area boundary ,the effect of blasting loads on the area that is 2m away from the boundary is smaller than that of the dynamic unloading of initial geostress which is similar to the blasting loads, for the rock which is certain distance away from the excavation outline, dynamic unloading of initial geostress is the main cause to the vibration of rock.（3） The response of rock-anchored beam under blasting vibration was researched, and the practical data was analyzed, then the response feature of rock-anchored under blasting vibration is determined and the blasting safety control criterion of rock-anchored is put forward. The bonding interface between rock-anchored beams and surrounding rock is the weakest place of the entire rock-anchored beam structure under blasting vibration. The effect of blasting vibration on rock-anchored beams may result in anchorage ability decrease, concrete intensity drop of the rock-anchored beams, rock-anchored beam concrete cracking, and bonding strength decrease between the rock-anchored beam and rock wall. The maximal horizontal tensile stress appears at top of the bonding interface, and the maximal vertical tensile stress appears at the top or the bottom of the bonding interface. 7cm/s can be adopted as the blasting safety control criterion of rock anchored which is older than 28 days.（4） The forecast method for damage zone induced by blasting excavation which is based on safety criterion by peak particle vibration velocity and the strength law of maximal tension stress is put forward, the damage zone induced by blasting excavation is confirmed. The enlarging excavation blasting of protective layer is the main reason to do damage to sidewall. Large decouple coefficient of charge should be used in the enlarging excavation blasting of protective layer. The damage zone of blasting usually just appears at the surface of the remaining rock mass. For smooth blasting, the incidence is about ten times of the borehole diameter.更多还原