在自然界中，由于地质运动岩体产生了大量的裂隙，构成了错综复杂的节理结构。这些裂隙节理会显著影响岩石的物理性质和力学性能。随着社会发展，隧道开挖、采矿工程等岩土工程的需求不断增加，这些工程在施工过程中会产生较强的应力波并会在岩体中传播从而导致内部裂隙扩展以至破碎，若对裂隙岩体问题处理不当，可能会威胁到施工人员的安全。

因此本文采用细粒花岗岩作为研究对象，分别制备了完整花岗岩试件、5种横向不同裂隙贯通程度与5种轴向不同裂隙贯通程度的花岗岩试件做为研究对象，测量了试件的质量、高度、直径、矿物组成等基本物理指标，基于霍普金森杆（SHPB）实验系统并结合高速摄像技术对不同贯通程度的花岗岩试件进行单次冲击试验。通过多组试验，研究不同贯通程度条件下的相关力学特性规律，从能量耗散角度分析不同贯通度对花岗岩试件能量传播的影响规律以及受到冲击时裂纹发展与损伤破裂的规律。主要得出了以下结论：

（1）利用SHPB装置，分别对横向与轴向方向上预制不同贯通程度（0%、10%、20%、30%、40%、50%）花岗岩试件并进行不同冲击气压下（p=0.11 MPa、0.13 MPa、0.15 MPa）冲击试验，计算并处理数据。研究发现在相同冲击气压下横向与轴向的动抗压强度与弹性模量都随着裂隙贯通率的增大而减小，峰值应变、平均应变率随着裂隙贯通率增大而增大。在同一贯通程度下，方向改变没有对峰值应力的变化规律有影响。在相同贯通程度下，试件的动抗压强度、峰值应变与平均应变率随着冲击气压的增大而增大，随着应变率的增加，动态弹性模量并不具备明显的应变率效应。

（2）利用比值法与能量方程分析了试件能量随横向与轴向裂隙贯通度与冲击气压的变化规律，并进一步对试件的能量吸收情况进行了量化，通过结果得知冲击气压对花岗岩试件入射能的影响较大而横向与轴向裂隙的贯通率的变化对花岗岩试件的入射能的影响较小，试件的入射能随着冲击气压的增大呈现出线性增长的趋势。随着冲击气压增加，反射能与透射能也随之增加。试件的反射能和吸收能占比随着贯通率的增加，其总体逐渐升高。透射能的占比随着贯通率的增加呈现下降趋势。

（3）利用高速摄影技术记录冲击过程。探讨横向与轴向不同贯通程度的裂隙在0.11 MPa的冲击气压下裂隙的发展情况，发现横向不同贯通裂隙试件在刚开始表面没有出现裂隙，随后试件上方出现轴向裂隙并迅速扩展直至预制裂隙面试件失去承载能力而破坏。由于有预制裂隙面的存在起到了缓冲的作用，使试件在受到冲击时下半部分仍然保持较为良好的状态。轴向不同贯通度裂隙花岗岩在0.11 MPa的冲击气压下，试件表面没有出现裂隙，压缩变形较小之后预制裂隙处的末端产生出了一条与轴向应力平行的张拉型裂纹，最后随着裂隙扩展将试件劈裂为两半。

（4）在试验后用标准筛筛分碎屑，通过对不同破碎程度的碎屑分析横向与轴向不同贯通程度的花岗岩的破碎情况。不同横向贯通程度花岗岩试件随着冲击气压的提高其破碎的程度逐渐增大，冲击剥落的碎块与岩粉数量也逐渐增多。在贯通程度较小（0%~20%）时在其长柱状碎块较多，在贯通程度较大（30%~50%）时试件短圆柱状碎块较多。不同轴向贯通度花岗岩试件在冲击气压增加后其破碎程度逐渐增大并由具有一定厚度的半圆柱状→细长柱状→三棱锥→粉末状碎屑转换 。

In nature, due to geological movements, a large number of fractures have occurred in rock masses, forming a complex joint structure. These fracture joints significantly affect the physical properties and mechanical performance of rocks. With social development, the demand for geotechnical engineering projects such as tunnel excavation and mining engineering is increasing. During the construction process of these projects, strong stress waves are generated and propagate through the rock mass, causing internal fractures to expand and eventually lead to fragmentation. If the issues of fractured rock masses are not properly addressed, they may pose a threat to the safety of construction workers.

Therefore, this study takes fine-grained granite as the research object and prepares three types of granite specimens: intact granite specimens, granite specimens with five different transverse fracture throughness levels, and granite specimens with five different axial fracture throughness levels. The basic physical properties of the specimens, such as mass, height, diameter, and mineral composition, were measured. Based on the Split Hopkinson Pressure Bar (SHPB) experimental system and combined with high-speed photography technology, single-impact experiments were conducted on granite specimens with different fracture throughness levels. Through multiple sets of experiments, the study investigates the mechanical properties of granite specimens under different fracture throughness conditions, analyzes the influence of fracture throughness on energy propagation in granite specimens from the perspective of energy dissipation, and examines the laws of crack development and damage rupture when subjected to impact. The main conclusions are as follows:

(1) Using the SHPB device, granite specimens with different transverse and axial fracture throughness levels (0%,10%, 20%, 30%, 40%, 50%) were subjected to impact tests under different impact air pressures (p = 0.11 MPa, 0.13 MPa, 0.15 MPa). The data were calculated and processed. The study found that under the same impact air pressure, both the dynamic compressive strength and elastic modulus of granite specimens decreased with increasing fracture throughness, while the peak strain and average strain rate increased with increasing fracture throughness. At the same fracture throughness level, the change in direction had no significant effect on the variation of peak stress. Under the same fracture throughness level, the dynamic compressive strength, peak strain, and average strain rate of the specimens increased with increasing impact air pressure. However, as the strain rate increased, the dynamic elastic modulus did not exhibit t a significant strain rate effect.

(2) The energy variation of the specimens with changes in transverse and axial fracture throughness and impact air pressure was analyzed using the ratio method and energy equations, and the energy absorption of the specimens was quantified. The results showed that the impact air pressure had a greater influence on the incident energy of the granite specimens, while the change in fracture throughness had a relatively smaller effect. The incident energy of the specimens increased linearly with increasing impact air pressure. As the impact air pressure increased, both the reflected energy and transmitted energy also increased. The proportion of reflected energy and absorbed energy of the specimens generally increased with increasing fracture throughness, while the proportion of transmitted energy decreased with increasing fracture throughness.

(3) High speed photography was used to record the impact process. The development of cracks with different transverse and axial penetration degrees under the impact pressure of 0.11mpa is discussed. It is found that there is no crack on the surface of the specimens with different transverse penetration cracks at the beginning, and then the axial crack appears above the specimen and expands rapidly until the prefabricated crack specimen loses its bearing capacity and is damaged. Because the existence of prefabricated crack surface plays a buffering role, the lower half of the specimen still remains in a relatively good state when impacted. Under the impact pressure of 0.11mpa for fractured granite with different axial penetration, there was no crack on the surface of the specimen. After the compression deformation was small, a tensile crack parallel to the axial stress was generated at the end of the prefabricated crack. Finally, the specimen was split into two halves with the crack propagation.

(4) After the test, the standard sieve was used to screen the debris, and the fragmentation of granite with different transverse and axial penetration degrees was analyzed through the debris with different fragmentation degrees. With the increase of impact pressure, the fragmentation degree of granite specimens with different transverse penetration degrees gradually increases, and the number of fragments and rock powder of impact spalling also gradually increases. When the penetration degree is small (0%~20%), there are more long cylindrical fragments, and when the penetration degree is large (30%~50%), there are more short cylindrical fragments. The fragmentation degree of granite specimens with different axial penetration increases gradually with the increase of impact pressure, and it changes from semi cylindrical to slender cylindrical → triangular pyramid → powdery debris with a certain thickness.

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