Experimental Research on Dynamic Response of Layered Medium under Impact Load
Round 1
Reviewer 1 Report
The paper deals with the dynamic response of layered medium under impact load. The effects of impact energy, number of joints, thickness of medium and joint layer, material properties of cementation layer and other factors on dynamic stress propagation and attenuation of layered media are analyzed by experimental test.
A numerical model is set to design the experiments. I understand that the numerical model is not the core of the paper, but some fundamental details are missing.
The experimental activity is interesting and well reported in the paper.
REMARKS
Line 106-108 The sentence is not clear.
Section 2.1.1 Please provide deatils about the performed analysis type.
Line 113 It is import to provide more detail about "Surface to surface contact is adopted"
Figure 1 Please report the constraints and comment it also in the text.
Line 118 Please provide more detail about this boundary conditions.
Line 125 Stress colud must be defined . Is it a direction/equivalent stress?
Figure 3 and comments in the text. Vertical/horizontal/radial direction are confused and not clearly reported. PPV is not defined.
Section 2.2 The description of the process for multilayer plates is missing.
Line 149 MPa instead of Mpa.
Section 2.3 Please report in the text and in figure 6 fixed constraint of the slab and report in the text if the experimental acceleration of the fixed point was monitored.
line 156 Vibration sensors are accelerometer? please report technical specification of the used sensors.
Figure 6 Please use Measurements point instead of vibration point.
Line 169 "By changing the thickness, the number of layers, the types of cementing layers, the thickness of cementing layers, the stacking order of slabs and the material collocation of cementing layers, the working conditions of different layered medium models subjected to impact load are simulated." NB the types of cementing layers, the stacking order of slabs and the material collocation of cementing layers, were not explained previously.
Section 3.1 Please insert a validation of the numerical results based on the experimental ones, before to discuss in depth all the experimental results.
Line 187 "different impact heights (H)" Instead of "different impact heights"
3.2 Please explain as the joint between plates is obtained (no material/material and thickness)
Line 246 "In the above test, the joint is treated as a two-dimensional plane without thickness" the sentence is ambiguous. the question is: The joint is treated as.. " or "the joint is.."
Line 253 The thickness of the filling material is missing.
Author Response
Please see the attachment
Author Response File: 
Author Response.doc
Reviewer 2 Report
In the paper “ Experimental research on the dynamic response of layered medium under impact load,” the authors studied the effects of impact energy, the number of joints, thickness of the medium and joint layer, including material properties of the cementation layer. They also analyzed different dynamic stress propagation and attenuation factors of layered media and modeling of the dynamic response of layered medium under impact load.
They observed that the thickness of the medium layer is the main factor affecting the vibration response of the layered medium in the impact test of the multi-layer slab. The simulation of the attenuation of the particle peak velocity was performed by modeling the hammer drop test on the three-layer concrete slab, using ANSYS/LS-DYNA numerical software. After experimental and simulation research the principal conclusions were: (i) Sadovsky's empirical formula can well fit the attenuation law of vertical peak particle velocity; (ii) the value of vertical peak particle velocity is larger and the attenuation law is more obvious with the increase of the number of layers and the decrease of the thickness of layers under the same total thickness of layered medium (iii) the thickness of cementing joint has a great influence on the wave propagation of layered medium and (iv) The dynamic response of multi-layer plate vary significantly ( considering cementing joints filled with different materials).
The work, as a whole, is of interest to researchers in science and engineering materials, especially for the theoretical and computational modeling of the processes or characteristics that occur in the layers and at the interfaces of concretes.
As a result, I agree to be published in this form, with the correction of minor spelling errors that appear in the manuscript, such as for example in line 149: 23.64 MPa.
Author Response
As required, minor spelling errors in the manuscript have been corrected.
