# Study on Dynamic Strain Distribution in Rock Broken by Abrasive Slurry Jet
## 1 Introduction  
In recent years, abrasive slurry jet (ASJ) and abrasive water jet (AWJ) have been widely applied to kinds of engineering works, such as material manufacturing, rock breaking, and so on [1; 2; 3]. In material manufacturing, [PERSON] studied the determination of vibration emission frequency depending on the impact of abrasive particles during stainless steel cutting with AWJ, and established prediction equations of the surface roughness parameters according to the vibration parameter and the traverse speed of the cutting head [4; 5]. [PERSON] used ASJ and AWJ to cut and drill glass, which showed that the ASJ has advantages in its performance of glass grooving and punching [6]. These works are useful for improving the quality of material manufacturing with water jets. In rock breaking with water jets, scholars have done a lot of research work and obtained numerous academic achievements. An experiment was carried out to study the rock cutting depth of abrasive water jet (AWJ) with the Taguchi experimental design method, which showed that the cut depths decreased with increasing traverse speed and decreasing abrasive size [7]. The processes of mechanical excavation assisted by water jets was studied, which showed that the contribution of the jet is to weaken the rock and to increase the stress [8]. [PERSON] developed a new kind of hard rock mechanical drilling technique with abrasive water jet assistance, which can reduce the impacting force and the bit wear in hard rock drilling [9]. With the mechanism of rock failure impacted by AWJ or ASJ regarded as the key to providing theoretical guidance for improving their efficiency in engineering work, it has gradually become aresearch hotspot. The finite element method (FEM) and smoothed particle hydrodynamics (SPH) were used to simulate the rock fragmentation process by water jet and the effects of impact velocity, confining pressure, and structure plane on rock dynamic fragmentation were discussed [10]. [PERSON] used the FEM and SPH method to investigate the mechanism and damage evolution of AWJ impaction on rock [11]. The results showed that the penetration depths are in relation to the shape and density of abrasive and the damage gradient is inversely proportional to the distance from the surface impacted by AWJ. The evolvement of rock damage impacted by high pressure water jet was simulated with nonlinear FEM and dynamic rock damage model. The numerical results showed that most rock damage and breakage takes place in several milliseconds, the main damage behavior under a general continual jet is tensile damage caused by the rock unloading and the jet impacting, and the evolvement of rock damage shows a step-change trend [12; 13]. The Arbitrary Lagrange Euler (ALE) fluid-solid coupling penalty function method was adopted to establish a model of rock breaking under AWJ with continuum damage mechanics and micro damage mechanics. The results showed that the body of rock damage and breakage is mainly attributed to impact and the internal process of breaking rock experienced three stages within 50 microseconds [14]. [PERSON] studied the capacity of pulsed water jets on rock breakage and finally found that the pulse lengths and pulsation frequencies of the water jet were the key parameters in generating the internal damage [15]. [PERSON] summarized the recent work on wear and erosion mechanics of rocks and cementitious composites and presented a definition of relevant wear types [16]. The Johnson-Holmquist-Concrete nonlinear constitutive model was used to study the formation, propagation, and attenuation of stress waves during rock breakage by pulsating jets, which showed that the effect of pulsating jets on the stress wave is very strong [17]. According to the above literature review, most of the papers focus on the capacity of water jets in rock cutting, while there are few studies on the dynamic stress strain distribution in rock, which is significant to reveal the mechanism of rock failure impacted by abrasive water jet.