*Selecting the Sensors to Measure Pavement Deflection*

There are several criteria to consider in order to select the appropriate geophones and accelerometers for the application of deflection measurement:


These criteria have led to select two types of geophones and two accelerometers, described in Figure 1.

**Figure 1.** Sensors used for instrumentation. **Figure 1.** Sensors used for instrumentation.

### **3. Pavement Modelling with Alize 3. Pavement Modelling with Alize**

There is a number of technical standards and documents followed for pavement structural design in France. In order to evaluate the response of the sensors mentioned and to define a reference deflection signal for conducting laboratory tests, the linear elastic software Alize is used [11]. This software is based on the theory of Burmister, which defines the solution for axisymmetric problems for a single uniform circular load pressure [12]. For this reason, a multilayer, linear elastic, semiinfinite and continuous pavement model is modeled using Alize. The interfaces can be considered bonded or sliding, depending on the pavement material being used. For this work, we have used bonded interfaces. It also uses a static pressure load on the pavement model to calculate the mechanical responses like horizontal and longitudinal strains and deflections. This software also There is a number of technical standards and documents followed for pavement structural design in France. In order to evaluate the response of the sensors mentioned and to define a reference deflection signal for conducting laboratory tests, the linear elastic software Alize is used [11]. This software is based on the theory of Burmister, which defines the solution for axisymmetric problems for a single uniform circular load pressure [12]. For this reason, a multilayer, linear elastic, semi-infinite and continuous pavement model is modeled using Alize. The interfaces can be considered bonded or sliding, depending on the pavement material being used. For this work, we have used bonded interfaces. It also uses a static pressure load on the pavement model to calculate the mechanical responses like horizontal and longitudinal strains and deflections. This software also includes a procedure for the back-calculation of pavement layer moduli. **Figure 1.** Sensors used for instrumentation. **3. Pavement Modelling with Alize**  There is a number of technical standards and documents followed for pavement structural design in France. In order to evaluate the response of the sensors mentioned and to define a reference deflection signal for conducting laboratory tests, the linear elastic software Alize is used [11]. This **Geophone (GS11D)**  • model: GS-11D • sensitivity: 89.2 V/m/s **Geophone ION** • Model LF-24 • sensitivity: 15.2 V/m/s **Accelerometer silicon design**  • Model 22106-002 • sensitivity: ±2 g **Accelerometer Model (MEMSIC)** • Model CXL04GP1 • sensitivity: ±4g

includes a procedure for the back-calculation of pavement layer moduli. The typical flexible pavement structure used to calculate the pavement response is defined in Table 1. The layer moduli correspond to standard values used in the French pavement design method for a wearing course bituminous concrete (BBSG), an unbound granular material of category 2, and a subgrade of intermediate bearing capacity [13]. The Poisson ratio was taken equal to 0.35 for all the pavement layers. The vehicle load considered is a 5-axle semi-trailer vehicle, with a total load of 40 tons. The deflection obtained with these parameters is defined in Figure 2. The typical flexible pavement structure used to calculate the pavement response is defined in Table 1. The layer moduli correspond to standard values used in the French pavement design method for a wearing course bituminous concrete (BBSG), an unbound granular material of category 2, and a subgrade of intermediate bearing capacity [13]. The Poisson ratio was taken equal to 0.35 for all the pavement layers. The vehicle load considered is a 5-axle semi-trailer vehicle, with a total load of 40 tons. The deflection obtained with these parameters is defined in Figure 2. software is based on the theory of Burmister, which defines the solution for axisymmetric problems for a single uniform circular load pressure [12]. For this reason, a multilayer, linear elastic, semiinfinite and continuous pavement model is modeled using Alize. The interfaces can be considered bonded or sliding, depending on the pavement material being used. For this work, we have used bonded interfaces. It also uses a static pressure load on the pavement model to calculate the mechanical responses like horizontal and longitudinal strains and deflections. This software also

**Table 1.** Pavement model. The typical flexible pavement structure used to calculate the pavement response is defined in

includes a procedure for the back-calculation of pavement layer moduli.

Bituminous mixture 7000 11 Unbound granular material 200 30 **Figure 2.** Deflection signal obtained with the ALIZE pavement-modelling software, corresponding to a 5-axle truck load. **Figure 2.** Deflection signal obtained with the ALIZE pavement-modelling software, corresponding to a 5-axle truck load.

Subgrade 80 250

**Materials Elastic Modulus(MPa) Thickness (cm)** 

Bituminous mixture 7000 11 Unbound granular material 200 30

Subgrade 80 250

**Materials Elastic Modulus(MPa) Thickness (cm)** 
