Effects of Loading Conditions on Fracture Processes near a charge hole in Blasting

爆破加载条件对装药孔附近断裂过程的影响

基本信息

批准号：
11650965
负责人：
NAKAMURA Yuichi
金额：
$ 2.05万
依托单位：
Yatsushiro National College of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

Fracture control is very important in rock excavation and partial demolition of concrete structures with blasting. In this research, effects of loading conditions on fracture processes near a charge hole were examined. The effectiveness of the decoupling of the charge, tamping, notched blast hole for blast crack control were studied experimentally.(1) Visualization system by the schlieren method and dynamic strain measurement system were constructed. A schlieren system using an Ar-ion laser was set up for visualization of stress waves and cracks in the blasting processes. A high-speed video camera system was used to record the dynamic events. In dynamic strain measurement, strain amplifiers with wide-band frequency characteristics (DC-500 kHz) were used. Strain signals were recorded in a digital storage-type oscilloscope with 8 bits vertical resolution.(2) Blasting experiments with PMMA blocks (100x100xl30mm, decoupling index ; 1.1, 2.57, 3.5) and an electric detonator were carried to … More analyze the decoupling effect on the motion of stress waves and fracturing near the charge hole. In this experiment, the fracture patterns formed in the block were also determined by the collection of fragments. High-speed video images showed that the optical clarity of the PMMA block near the free surfaces is lost by the tension of stress waves. The dynamic fracture processes near the charge hole are changed as the decoupling index increases. The strain measurements showed that an air cavity between the charge and the walls of the charge hole causes influencs to the compressive wave propagation in the medium.(3) Blasting experiments with mortar and concrete specimens (200 mm in dia. , 200 mm in length, decoupling index ; 1.1, 1.86, 2.57, 4.85) were carried out to demonstrate the effectiveness of the decoupling of the charge, tamping, notched blast hole for blast crack control. High-speed video images showed that the cracks propagate from the charge hole towards the free surface, and that the decoupling of the charge is effective in controlling crack initiation from the notched charge hole and in producing controlled fracture plane. Less

断裂控制在岩石发掘和通过爆破的混凝土结构的部分拆除中非常重要。在这项研究中，检查了加载条件对电荷孔附近断裂过程的影响。通过实验研究了电荷解耦，对爆裂裂纹控制的挖掘，切口的爆炸孔的有效性。（1）构建了通过Schlieren方法和动态应变测量系统的可视化系统。建立了使用AR-ION激光器的Schlieren系统，以可视化爆破过程中的应力波和裂纹。高速摄像机系统用于记录动态事件。在动态应变测量中，使用了具有宽带频率特征的应变放大器（DC-500 kHz）。应变信号记录在具有8位垂直分辨率的数字存储型示波器中。（2）使用PMMA块（100x100xl30mm，Deconpling Index; 1.1，2.57，3.5）进行爆破实验，并将电力雷管用于…更及其对电压浪潮的移动效果更大的分析效果，并接近付费孔。接近孔和FRICT OFFER速度。在该实验中，块中形成的断裂模式也由碎片收集确定。高速视频图像显示了自由表面附近的PMMA块的光学清晰度因应力波的张力而丢失。随着解耦指数的增加，电荷孔附近的动态断裂过程会更改。应变测量表明，电荷孔的电荷和壁之间的空气腔会影响介质中的压缩波传播。（3）用砂浆和混凝土样品进行爆破实验（DIA。，200毫米，长度为200毫米，长度为200毫米，将索引; 1.1，1.1，1.86，2.57，4.85）被置于指数的指示，该均为指数的指数，该指数均为指示效果，该指数均被录制。用于爆炸裂纹控制的切口爆炸孔。高速视频图像显示，裂纹从电荷孔传播到自由表面，并且电荷的解耦有效地控制了从缺口电荷孔和产生受控的断裂平面的裂纹倡议。较少的