The performance and application of DD-110 Vibratory roller

In highway construction, the compaction process is the one with the largest input of work and the most requirements for quality and technical indicators, especially for the construction of asphalt pavement. The construction of asphalt pavement mainly includes three aspects: mixing, paving and compaction. Compaction is a crucial step, which has a significant impact on various technical indicators, such as flatness and density. To achieve good quality indicators during the compaction process, it is necessary to have a relatively comprehensive understanding of the selection of road rollers and the performance of each model of road rollers. During the asphalt pavement construction of the Bolai Expressway, we, through argumentation and reference to the practices of sister units, configured Ingersoll Rand DD-110 vibratory rollers as the main compaction machinery, which played an important role in the high-speed and high-quality paving of the Bolai Highway. The following is an analysis of the various data and performance requirements of the DD-110 vibratory roller in highway construction.

The function of dual drive and dual vibration of 1DD-110

1.1 Dual drive effect

The forces exerted by the driving wheel on the compacted material are H '=H and R' =R. The vertical force R 'compacts the material, while the horizontal force H' causes the material to move in the opposite direction of the roller's travel. This movement will be resisted by the already compacted material behind the driving wheel, causing the moving material particles to fall into the high-pressure zone close to the vertical line of the roller and be compacted. Therefore, no wavy surface will form in front of the driving wheel, and the surface of the compacted material will be quite flat. Due to the dual-wheel drive structure adopted by the DD-110 roller, it has excellent performance during compaction and will not produce wave phenomena, thus ensuring the smoothness of the compacted road surface. Therefore, this all-wheel drive roller can also be called a wave-free roller, which is precisely a hard requirement that expressways must meet.

1.2 Dual boosting effect

Vibration can sharply reduce the internal friction of the compressed material, lower the shear strength, and thus make the compressive resistance very small. It is extremely easy to expel the gas and liquid in the compressed material, allowing them to interlock and achieve compactness. Due to the dual-wheel vibration function of DD-110, the compaction efficiency can be greatly improved during the compaction process. For asphalt pavement, it is more conducive to the formation of the pavement and ensuring the construction quality.

Selection of amplitude and frequency for 2DD-110

The compaction effect of a roller is mainly determined by the linear pressure of the roller wheels, and the selection of different linear pressures depends on the strength of the stone materials used in the pavement layer and the load-bearing capacity that should be achieved after compaction.

Table 1 is a comparison table of the strength of stone materials and the line pressure required by the roller, and Table 2 shows the line pressure values required for several main materials.

Due to the dual-frequency 8-amplitude feature of the DD-110 roller, its application range has been greatly expanded. During operation, it can have multiple working modes, that is, multiple linear pressures can be provided. The linear pressure of the roller under various working conditions can be calculated based on the data provided in Table 3 and combined with formula (1). The conversion of the working mode of DD-110 is quite simple and fast. It can be reasonably selected based on the material properties, compaction thickness and some other indicators (refer to Tables 1 and 2), thus having a wide range of applications. Calculation of linear pressure for vibratory rollers: Unit linear pressure

Table 1 Comparison Table of Stone Strength and Required Line Pressure of Roller

The stone material is soft, moderately hard and extremely hard

Stone material name: Limestone, sandstone Limestone, sandstone

Coarse-grained granite, fine-grained granite and basalt

Ultimate strength: 300-600, 400-1000, 1000-2000, above 2000

Road roller line pressure

(kg/cm) 60-70 70-80 80-100 100-125

Table 2 Linear pressure of Several main materials

The linear pressure of the rolling wheels required at each stage of the lay-up form (kg/cm) and the speed required at each stage of rolling (km/h)

Water-borne crushed stone pavement: 30 to 40, 40 to 50,80 to 120 1.5 to 2,1.5 to 2,3 to 4

Asphalt concrete: 30 to 40, 40 to 75,50 to 75, 1.5 to 2,2.5 to 3,2 to 4

Asphalt crushed stone: 30 to 40, 50 to 75 2 to 4

Figure 2 shows the overloading coefficient of the real-time linear pressure or contact pressure of the vibration pressure

Table 3DD-110 Vibratory Roller Vibration Frequency, Amplitude and Excitation Force List kN

Vibration frequency

(Hz) Amplitude (mm)

0.46 0.51 0.58 0.71 0.81 0.89 0.91 0.94

42 65.2 70.7 83.7 98.8 112.9 124 131.1 133.4

31 35.7 38.7 45.8 54.1 61.8 67.9 71.8 73.1

The advantages of the 3DD-110 frequency design

The relationship between compaction effect and vibration frequency and amplitude. As can be seen from the figure, the maximum range of vibration frequency and amplitude affecting the compaction effect is between 25 and 50. If the amplitude is increased at the same frequency, the compaction effect and influence depth will be significantly improved. And the DD-110 with 8 amplitude adjustments will truly reflect this "improvement". For the compaction of asphalt materials, the optimal amplitude is 0.4 to 0.8mm, and the applicable frequency is 33 to 50Hz. Based on the actual thickness of the asphalt material during construction and the material conditions, the recommended amplitude adjustment values for the hot asphalt mixture, base layer and subbase layer are shown in Table 4.

Table 4 Construction Thickness and Amplitude of Asphalt Material

Material thickness (cm) : 2.54, 2.54-6.35, 7.62-10.16, 11.4-15.2, above 15.2

The amplitude Settings are not 1,2,3, 2,3,4, 4,5,6,7, 5,6,7,8

In construction practice, we have realized that when using vibratory rollers to compact the surface layer, high frequency and small amplitude should be adopted. When compacting the base layer, low frequency and large amplitude should be adopted. In addition, it should be noted that during the vibration process, larger mass particles are subjected to greater inertial forces and first detach from adjacent particles and move downward. Therefore, during the compaction process, due to the difference in particle size, if the vibration lasts for a long time, delamination will occur. Thus, the vibration should end when the maximum density is achieved and the pores between large particles are filled by small particles. Therefore, based on experience, it is recommended that the vibration time of asphalt mixture be 1 to 1.5 minutes, and that of clay be 1.5 minutes.

4. Compaction speed

The DD-110 adopts a stepless speed change ranging from 0 to 14.8km/h, which is highly suitable for compaction of various paving layers. The following compaction speeds are recommended: 3 to 6km/h for soil and 1.5 to 4km/h for asphalt. In addition, the perfect combination of the wide wheel width and vibration of the DD-110 not only accelerates the compaction speed and reduces the number of compaction passes, but also significantly reduces and lightens the wheel marks.

In addition, the DD-110 machine not only has the functions of a static roller but also can control the vibration point by speed through an automatic function. Its advanced instrument monitoring system, full hydraulic transmission, and flexible operation provide reliable guarantees for its use and have played an important role in the construction of the Bolai Highway.