Probably need:
pinMode(ACCEL_CS, OUTPUT);
pinMode(ACCEL_SCK, OUTPUT);
pinMode(ACCEL_DI, OUTPUT);
pinMode(ACCEL_DO, INPUT);
You don't seem to include any output in your sketch so I don't understand how you detect if it is working or not.
You can remove references to the SPI library since the adxl345_read() function does software SPI.